Well, I played both of those demos I got last night. I tried out Jak3 first because I haven't played any of those games before. It seemed kinda weird, but probably because I wasn't used to playing it. I half-expected it to be similar to Ratchet & Clank, though I probably shouldn't make assumptions like that. If I did plan on getting it, I most likely will want to start from the beginning. The fairly lengthy opening movie had a lot of stull I think I would only understand from playing the first two game.
Up Your Arsenal on the other hand, of course, will be great. I could care less about how it plays so much the same as the last games because that's what I love! I can't wait til November 2nd to go through another one of their awesome adventures and waste enemies with all-new weapons. The best on the demo had to be the Plasma Whip. The new Captain Qwark mini-game was pretty funny too.