Wishbone: The first is early full-3D games. I like Doom, Duke3D etc. well enough, but they used sprites for the models instead of polygon models. However, the earliest games using polygons for everything really haven't aged well. Actually, to be honest, they looked like crap even back then. And the very worst of them were the ones who had no good reason to use 3D in the first place, like Simon the Sorceror 3D. Lots of games were made in 3D at the time, simply because "you had to use 3D", according to the studio/publisher execs of the period. In many cases, it was a poor choice.
This is pretty much how I feel about the PSone. With a few notable exceptions, the vast majority of full 3D PSone games (that weren't racing games at least) sucked ass. Most of the titles that people rave about - like Final Fantasy 7 - had prerendered backgrounds, and even that looks pretty crap these days.
There were some games that used the PSone's hardware limitations to its advantages and eked out their own art style that could be easily reproduced on the console - Crash Bandicoot with its textureless, gouraud-shaded figures comes immediately to mind.
As I say, there were a few exceptions - Metal Gear Solid, Gran Turismo, Wipeout, Resident Evil 2 and 3, Rage Racer and Ridge Type 4 - but the majority of 3D games were 3D for the sake of being 3D.
Of course, now games feel the distinct need to be 2D, no matter how crap they are, just so that they can lay claim to being "indie" and "cool".