Quake 1, and Quake 2 are some of my favorite games of all time. They had simplicity, they had darkness, they had evil. The levels were great, forboding, and above all dark. The monsters were generally good, not quite your serious sam charging bull good, but for there time amazing. Quake 2 incorperated great netplay, helped not only by what was for the time stunning netcode, but also by the weapons themself. You cant not love the Quake 2 Chaingun, and rocket launcher.
Quake 3 was at least in my opinion an experiment. ID wanted to know if they could create a game within the Quake universe, having no substance other then Arena combat. They also wanted to capitalize on the multiplayer movement, moving almost exclusively to the online format. All this is well and good, and in and of itself wouldnt have hurt the game one bit. The problem came when the lighting changed. Quake for me anyway was always about atmosphere, hell all the way back to Doom you could see this. Doom 2's shareware demo ended GREAT, you fall into a pit of death with hundreds of baddys all in close quarters. best part is ITS DARK.
Look at Q3A's levels, most of them are dark, somewhat anyway. The 3rd party release maps are much better. But Q2 was all about the dark, it made you think you had pissed someone off and ended up in there own little hell. For me anyway the biggest problem was the weapons, they're no fun, asside from the dubble shotgun, and the machine pistol they just are soo....blah.
If you hate Q3A do me one favor before you write it off though, grab 6 or so friends more the better and play a lan game. That is the only way the game is really any fun. Granted ANY game improves via lans, but Q3A starts to shine.
My Cisco CCNA class got bored and put the Q3 demo on most of the machines in the class, it looked like crap(ati rage pro's) but i have to tell you it was amazing fun. Nothing like jumping out of no where with a dubble barreled shotgun and turning your best friend into little gibs....and taunting him face 2 face.