I'm not saying it's going to be just like Half-Life 2 all that much, I just think that it might be a valid comparison in the smoke and mirrors department. I don't think it's going to be on rails to the same extent, and really, I don't care that much about rails either. If it's fun to play and a memorable experience, then that's great. A lot of memorable stuff in games (like HL2) comes from scripting, which is by its nature on rails, and I wouldn't be surprised if Resistance used quite a bit as well.
I have quite a bit of faith in Insomniac as well, and it's good to see them taking a break from Ratchet I must say.
BTW, Gears of War reminds me less of Doom 3 than Resistance of HL2... but maybe that's just my bias toward Half-Life 2 and Gears (which doesn't remind me of too much really). I look forward to when Resistance and Gears are actually out and can stand on their own (if they're as good as we're all hoping anyway). Then games can be like Gears or Resistance instead of like Doom or Half Life, oh boy!