I've had the "opportunity" to try both Samsung VR and Daydream VR.

They're both s***.

They're missing so much of what's necessary to build a proper "VR" experience like you'd find on a Rift or Vive.

I want to talk about why, because I feel like almost everyone else is so busy being wowed that they're missing the point.

First off: pixel density.
The phone market already suffers from laziness in physical pixel density. Google Pixel (non-XL), OnePlus 3, Most Motos...tons of well-regarded phones have pixels big enough to count at normal reading distance. On relatively pixel dense phones (those under 6'' at 1440p) we're finally getting to the point where individual pixels are tough to distinguish, but PenTile* being the prevaling AMOLED tech still gets in the way there. I have a very pixel-dense phone (534 PPI) and I can still count individual pixels because of the sub-optimal PenTile pixel arrangement.
Then you throw that phone in a headset with magnifying lenses and suddenly it's like looking at a world built from multicolor legos.
NOTHING is sharp.
Colors are badly delivered (again, a problem worsened by PenTile). There's no white. There's no black if you have an LCD (AMOLED's advantage is highlighted here).
Text looks like it's being rendered on an Apple ][ with subpixel rendering and can be completely unreadable at times.
There's aliasing the likes of which I haven't seen since playing Ultima Underworld on my VGA CRT in the '90s, and that aliasing is infinitely more noticeable as it changes and mutates with the slightest head motion.

Secondly (and arguably more critical to the overall "VR-ness" of the experience if less important in overall end-user impact):
These phone-based headsets ONLY register ROTATIONAL motion. They do not register any kind of lateral motion. That means that when you're viewing Netflix in VR mode (I'll get to this later, don't worry) and want to lean closer to the screen or look closely at items around the room, you can't. Leaning forward does nothing to the VR perspective.
This is CATASTROPHICALLY UN-IMMERSIVE and IMMEDIATELY AND CONTINUOUSLY FATALLY BREAKS THE EFFECT OF VR. You simply cannot have a VR experience without lateral motion recognition. It will never work. ANYONE who puts a headset on is going to try to lean close to something and find that it doesn't work. More subtly, you end up re-training your head movements because normal head movements don't have the expected results. The device is constantly reminding you that it doesn't really work, but all the while begging you to explore the space around you. It's a self-diminishing cycle that just becomes obnoxious.
A few programs give you the ability to use the input device to "zoom" the view, but while a functional workaround, this really only serves to highlight just how critical lateral motion recognition is to the complete VR experience.

Thirdly:
There is ABSOLUTELY NOTHING WORTHWHILE TO DO IN DAYDREAM OR SAMSUNG VR.
Not one damn thing.
There are some bad jump-scare "games" that remind me of the bad old days of smartphone app stores and sh@tty cash-in PC shovelware.
There are a bunch of video player "theater modes."
There's Google Streetview VR.
And there are a bunch of "games" that are all but unplayable due to input-method and viewport-tracking limitations.
That's all.
NONE of this is worth anyone's time.
I obtained a Daydream VR headset at a hefty discount (I never would have even cared about it otherwise) and after an hour with it, I have more than exhausted the content available for the format. I will probably never use it again, except to show other people how stupid it is.

Fourthly:
That input method issue.
Samsung VR is terrible here. There's a sort of capacitive d-pad thing on the right side of the headset. Most apps avoid using it at all costs because it's clunky and awkward and not well tactil-ly indicated. As a result, in Samsung VR you generally make selections by looking at an object for an extended period of time. This is the single worst input method I've ever experienced in my entire life of playing with electronics.

Daydream VR is better. It comes with a controller that's basically what would happen if a Wiimote and a Steam Controller figured out how to breed. It's also strongly reminiscent of the Nexus Player controller, for those who have used that. It's a small, two-inch-long remote with a curved bottom and a flat top. The top has three buttons and a circular touchpad (a-la Steam Controller/Vive) that falls under your thumb. The third button is basically the whole touchpad-end of the controller, so pressing the touchpad clicks this button. The other two buttons are an application-specific function button and the Home button. Oh, it does have volume controls as well, which is smart since Daydream will support a variety of phones with different physical volume button layouts.
Anyway, the Daydream controller has motion sensing and seems pretty accurate (on par with or better than a Wiimote Plus). In most programs, you get a nice transparent 3D representation of the remote in the VR perspective to help with spacial orientation. Others swap it out for a sword or wand or hand, etc.
This is a much better means for interacting with programs in VR mode. Selecting a video to play is simple. Selecting an app to launch is natural. Even text input is generally doable.
But it's still crap. It's still a step down from a touchscreen, which was already a terrible input method for anything interactive or dynamic.

Fifth:
FoV and viewing distance.

I spent about 45 minutes with my headset on the other day. Then I took it off and sat down at my PC to play a real game. After a few minutes, I realized something.
I was still moving my head and body around as though I was wearing the headset. And by that I mean a few things:
1: I was moving my head and not my eyes.
2: I was moving my shoulders and neck to stabilize the pivot-point for head movements and avoid lateral motion.
3: My mental focal area was TINY. Humans have a pretty broad field-of-view, but I was using only the tiny forward area that the VR headset tends to keep within good focus.
4: I kept thinking how FAR AWAY everything was. Which is weird, because the whole point of VR is to open up a big virtual space around you. But because of the focal distance of the headset, my brain is still smart enough to know something's not right. So even though the headset can present me with a big, open wilderness to look around, it's a big-open wilderness that's RIGHT IN YOUR FACE and the crappy phone-based VR isn't going to fool a human brain that processes real multidimensional inputs all the time without breaking a sweat.

I have what amounts to a 5-monitor setup in my (home) office (3 monitors on the desktop, generally with a laptop at either end) for multi-tasking and productivity. I'm very used to making heavy use of all available screen real estate. But after wearing the headset for a bit, I found that I sort of had to retrain my eyes and brain to utilize all that space. I had gained a sort of weird temporary myopia. My primary monitor is just a 24'' 16:9, but playing a few motion/action-intensive games where things happen all over the screen, I realized I wasn't focusing on the outer corners. I'm not sure, but I would wager this is due to two things: The first being VR's use of lenses to compensate for focal distance, which causes distortion at the outer edges of the already tiny FoV and the fact that most VR interfaces are designed to take up only a small portion of that narrow FoV to avoid being nonfunctional.


So, basically, in summary, the next time someone tries to show you how FREAKING MINDBLOWING their new VR headset is and then hands you their phone, tell them to go to Best Buy and demo a Rift or Vive, because these portable excuses for VR are just lowering everybody's standards for what VR should be.

*Oh, and for those who don't know, PenTile is a pixel arrangement that places pixels in a sort of diamond configuration rather than a clean 1x1 grid of pixels. Where traditional displays alternate red, green, and blue pixels horizontally and stack rows vertically, PenTile has a 2-dimensional pixel color alternation that emphasizes green for human-eye-friendliness reasons. But what this ends up creating is a pixel rendering space that has no clean edges and isn't very good at rendering whites because of the rGb imbalance. Nothing ever looks sharp or crisp and the only way around that is to make the pixel density so high that the fuzzy edges are too small to see. But even on very high (500+ DPI) displays, they're still not small enough (even outside a VR headset), and it has negative effects on text and contrasting color reproduction.