My one hope for ME4 is for it to have better facial animations, to better replicate emotions. Looking at these character's blank expressions is tiresome. I'm sure they'll be able to do it, with whatever engine they use next -- Frostbite or UT4 or w/e.
Maybe Frostbite will make it easier, but facial animations have only gotten worse throughout the series, and that's down the development making them less and less of priority.
1 was a cavalcade of characters that had every right to be interesting, but just weren't. There's a reason the cast substantially changes in 2.
The people themselves weren't as interesting (read: forced) in ME1, but the fact tthat they were providing context for this brand new and interesting world made them very engaging.
ME2 has two standout characters, Moridin and Legion, but that's two out of a total of 12 characters that all add virtually nothing. They aren't interesting on their own because squad mates in ME2 are much more 2 dimensional archetypes than anyone in ME1, and generally contribute nothing to the mythos. Those that do, Samara for example with the Asari Justicar, are very one note, plain and cliche. The only two exceptions to this are Legion and Moridin, and thane to a degree, since he provides great insight into the Hanar.
On an individual basis Moridin and Legion are probably better than any ME squadmate, but as a whole the ME2 cast is a cavalcade generic stereotypes that aren't interesting within the context of the world or as people to speak to.
EDIT: Miranda provided decent insight into Cerberus, but the retconning on them made it all a bit much to swallow.
