Gen 4
Can't help you with comments on a Gen5, but I like my Gen4,and its a better IDPA match pistol than I am competitor. Stone cold reliable, accurate with good ammo (had a BAD match once with poor reloads....my own!) I've found the 5" barrel boosts velocity in SD ammo too, and occassionally carry the G34...I shoot the longer tube better due to the longer sight radius.
Criticism is usually leveled at the Glock plastic sights, but lots of good aftermarket options when one finally goes that route (I have not,but should).
I did not find the Gen 4 trigger as slick as Gen 3's, and an aftermarket connector did not help. There was a discernible "stack" or speed bump halfway back.........which likely could be used to prep the shot,but I like a smooth consistent trigger all the way. I just live with it. I like the Gen 4 mag button, the grip inserts are interesting (I shoot the big one) , and I have no complaints about the Gen 4 checkering.
I DO wish Glock would used cut/conventional rifling, so that lead bullets (cheaper) could be shot.