Well, take this for what you will, this is the first HDTV I've owned.
I did a lot of research into various HDTVs, and found what seemed to be a general consensus that Sony, Sharp, and Panasonic are some of the best to get. However, I saw some positive buzz after Black Friday about the Westinghouse TVs as well, and I haven't heard of too many hardware failures, so...
... I bought one. I had intended to get the Olevia at Circuit City, but after dropping by the Best Buy, I saw this one. It looked much better, and actually looked quite comparable to the Sony 32" that was sitting right next to it. It may not have had as smooth a color gradient, but it was close, and the image is very punchy.
I think what sealed the deal for me was the number of inputs on the sucker. 2 HDMI, 2 Component, 2 S-Video / Composite, VGA, and Coax, which pretty much covers the entire spectrum of my consoles (including my Dreamcast VGA Box, whee!).
I didn't notice any lag time at all with my gaming. I think I was imagining some with the emulators I was running on my Xbox, but after trying it on my older TV, I think it's just mushy buttons that were the culprit there. Plopping Burnout 3 in worked like a charm, and if you can't detect lag there, you're not going to detect it anywhere, as fast as that game is. And I didn't notice any, and the screen stayed nice and crisp throughout. And it's BRIGHT. Whites look much brighter than anything I saw on my SD 27" Panasonic.
I noticed the speakers weren't all that great. They didn't have much bass to speak of, but I didn't spend any time mucking around with 'em, instead turning them off and resorting solely to my set of cheapy $30 Wal-Mart speakers. That's plenty good enough, and rectified that problem on the spot.
All I've really seen is the UnleashX dashboard in 720p, and it's REALLY clear. But moving images may be another story, but I'm guessing after seeing Burnout, it's not going to be a problem, especially given 720p being the actual native resolution of the screen.
I did detect some slight skip when I had the SNES hooked up when fast motion occurred on the S-Video inputs, but I think that's either a problem with the cable not liking the SNES, or just the SNES signal in general. The same S-Video cable looked perfect on the PS2, which is what it was made for, anyway (one of those three-system cables).
All in all, I am VERY pleased with the TV, and of course, in my paranoia, picked up the $99 service plan, so I can return it within four years for repair if anything goes wrong. In my opinion, if you do that, you can't go wrong.
Now, without owning another HD, I can't provide any sort of long-term comparison, and really, this isn't even a long-term review, but I like it, and things seem to be going swimmingly right now. Needless to say, I'm more tempted than ever to get an Xbox 360, so I'll have the whole "Wii60" thing going.
Hope that helps at least a little bit. If anyone has a differing opinion, feel free to post.