[update 2007-1126: replaced "synopsis" in the title with the more accurate "bullet-point review".]
* Custom character creation is great if you are good at making decent-looking characters. I'd wanted to make a Francis Urquhart clone, but since characters seem to be limited to age 30 plus or minus five years, I had to do a lot of adapting. Nonetheless my character's face ended up with a lot of personality, and much more interesting to watch than the default lunkhead. Saint's Row is still the gold standard for facial customization in 360 games, IMHO, but this is pretty good.
* Long playtime. I got over 30 hours and only did maybe 1/3 of the side-quests and Mako exploration (which is great fun when the mountains aren't too steep).
* I guess that deserves its own bullet point. Exploring with the Mako is very enjoyable.
* The galaxy-wide setting is interesting and the storyline keeps you involved, even if it isn't exactly Shakespeare.
* The conversation wheel is a nice way to handle dialogue. You get a brief description of the "mood" of your response and the game takes it from there.
* Once you get the hang of combat, it is really entertaining -- on Easy level it seems like most combats are over before they even got started. This may be the first RPG where I actually wished there was more combat in it. (Eh, come to think of it, I probably felt that way about Jade Empire too.)
* When entering new areas, hi-res textures pop in, sometimes several seconds after entering area.
* Auto-save system is almost completely useless. Save early and often.
* Menu system isn't bad once you get used to it, except for one thing: there's no easy way of evaluating the power of an item when you're wondering if you should sell it. In shops you can compare it to your active character's equipment, but not that of the six other characters you've outfitted. You can roughly go by the Roman numerals in the name -- e.g., when most of your characters have level IV equipment, you can safely sell off the level I and II stuff -- but that's kind of hacky.
* Once the main story is done, you can't continue on and explore those areas that you left unexplored because the Galaxy was at risk and time was a-wastin'. And by the end, even if you're in the habit of keeping the three or four most recent saves you won't be able to restore to a point where you can finish up the side stuff.
* A lot of your conversation wheel responses don't map very clearly to the actual spoken response. (For example, you could choose something like "Screw you!" and your character might say "I'm not sure about that," or choose "Good job!" and your character might say "Carry on, Lieutenant.") And a lot of choices are just between three ways of saying the same thing. (Good luck trying to find a way to sympathize with Ashley's distaste for aliens, Commander Politically Correct.)
A good game, definitely worth playing. But the developers left a fair amount of room for improvement in the sequels.