It was appalling, it could have been ok but it distracted from the characters and storyline. Nothing much happened and that should have been a very dramatic episode. It didn't showcase the emotions well in my opinion. I was very dissapointed. However, i can understand why some people liked it, it was original after all.
It was definitely weird at times, but when Sara Ramirez and Chandra Wilson are leading the singing, you know it's gonna be worthwhile. I was pleasantly surprised by the cast's singing ability. They definitely could never do it again, but I think it worked. Plus, having all grey's songs made it a nice trip down memory lane-- "oh, this is what played when denny died," or "Hey, this is the MerDer prom sex song!"
BTW, Emerode, if you "don't want to be a snob," don't make blanket statements. Sara is an award-winning broadway actress, and Chandra has also been on broadway. I think if "no one could sing" that wouldn't be the case.