Assassin's Creed PSP:
I'm about an hour and half through the game. The game is essentially AC1 portable with a few changes.
Less people: kinda given but they address it in the story (abeit poorly)
The game seems to be waaay more linear than AC1 ever was (kinda like AC2). No more investigation missions (not I've seen anyways) Just one story mission to another. All the odd job missions are still there, and completing them nets you templar coins, which you can also find in the environment.
Open world is ... well, separated by load screens. Remember individual city sections in AC1? Its broken up with gates and loading. Areas are still relatively big though.
Man playing this on the Go while I play AC2 on the console at home couldn't be better. The templar coins you collect turn into money for AC2 (which is very much needed FYI) And the health upgrades you get in AC2 are funneled back into the PSP version.
The framerate is steady but there is lots of pop-in (though not as much as AC2).
I play it with the HUD off and so far its been a great ride. I do not suspect that this story will be anything major within the franchise (well as far as I've gotten). But IMO its recommended to people who enjoy the AC franchise (and maybe even playing AC2 ATM).
EDIT: Camera is handled by the L trigger. Tap to center, hold + face buttons to pan. Don't have a lot of problems with it.