I currently own three Colt 1911s, and just picked up a RIA 1911-A1 as my "tinker/plinker/stinker" 1911 (and picked one up for the wife - paid $295 each). I can't really put in too much opinion here, as the wife's RIA and mine only have about 200 rounds, each through them, so far.
Mine - Has functioned flawlessly and is quite accurate at 15 yds. Didn't like to release the slide with the supplied empty mag (even when using both thumbs with a lot of force), two "el cheapo" mags that work wonderfully in all my Colts won't work with the RIA, and my metalform "Colt" mag that came with my 1989 Government model Colt works well. The sites aren't too bad, but I painted the ramp flourescent green and did a goal-post outline of the rear one in white. The finish seems to scratch a bit easily. Hammer-bite almost seems to be more than my Colts, but I didn't shoot them side-by-side. I also added some Hogue, finger-groove rubber grips. Thinking of installing a beavertail.
Wife's - Had the same magazine issues that mine had. The gun had two FTF, as the round didn't go completely to battery. This was solved with more oil on the rails. Painted the sites the same as mine. She has shot both guns and says hers shoots better for her. I haven't shot her RIA, yet.
* The slide release got much better the more I played with them. Also, both guns have only eaten WWB 230 gr FMJ, so far.