I like pretty graphics, but I'm not going to turn a game away because it's ugly, nor am I likely to buy one just because it's pretty. About the only game that I've played with graphics so bad that they negatively impacted my experience was Final Fantasy IV, which literally hurt my eyes if I played the desert scenes in a darkened room. Also, PC games old enough to have CGA be the only graphics mode possible don't get much play from me, although if I find one that's a good enough game, and that the graphics don't make it impossible to play, I'll still play it. Hercules modes, and anything from EGA on, tend to be playable for me.
I think the best anecdote about my approach to graphics is Half Life. I'm playing it with the original models, instead of the HD pack, but I'm also forcing Anti Aliasing, Ansitropic Filtering, and Vsync through my graphics card drivers. I'd still play it if I couldn't do that, but since I have the tools to make it look better, I'll use them. (I'm not using the HD models because they change some of the weapons, and also break compatibility with some mods.)