Of the top of my head the bad things that immediately jump out
Window motors in the '03 & '04 frequently go bad
Inferior interior materials (probably not a big deal for you)
Second to third gear change grinds because of synchro setup (fixed in the later CD009 transmissions)
Tons of good though...
Made in great numbers so parts are plentiful both new and from wrecked Zs
Everything that can be done most likely has been done by someone, so you can learn from others' successes and failures
Welcome to NICO!