Obsidian Entertainment are the developers of the original Fallout 1 and 2 also the of imo best western RPG ever, Planescape Torment. They where also assisting Bioware with Baldurs Gate 1, 2 and all expansions. And lets not forget that they where the developers of KOTOR 2. They got quite a good history with games and imo are 2nd best RPG developer after Bioware.
And with Bethesda Softworks in the seat and these guys assisting, i don't really see why this shouldn't be better than Fallout 3 which imo is the 2nd best "RPG" this generation, although ME2 isn't really a RPG, its better nonetheless.
Long story short this is currently my most anticipated game of this year.