My group of three had dinner there last October. Granted we were in a bit of a hurry to get to MK for Spectro, but I'll try to remember what I can.
-Portions were not gigantic, but I don't remember leaving hungry. The selection was decent but not extravagant. I had the beef medallion and it was about the portion I would expect from an upscale non-Disney restaurant. The deserts are notable, however, as they are all served as a trio of small offerings that compliment one another. I had the "Crispy and Crunchy," as I love pineapple, and was not disappointed.
The menu is available as a PDF from the main disney site here:
http://disneyworld.disney.go.com/resorts/contemporary-resort/dining/the-wave-restaurant/ Look for the menu links near the bottom right of the page.
-Atmosphere was okay. The decor is very nice but doesn't necessarily feel as "upscale" as California Grill. It was pleasant enough but definitely not intimate if that's what you're looking for. My fiance noted that it was pretty loud in there; lots of families. If you're looking for a place to get away from Mickey and Co. for an hour or so, it's not too bad, as the look of the place doesn't have mouse ears on every wall sconce. We had a table right in the middle of the room, which naturally probably wasn't as nice as a booth might have been, but didn't feel cramped.
-Of note is the fact that while we were having difficulty getting any reservations to use up some table service meals while we were there, we got into The Wave by calling that very morning. Resort restaurants aside from the high-end eateries are generally easier, and this one is close enough to MK that you can pop over for lunch/dinner easily and then go right back to the park if you like.
In conclusion: It's a pretty decent meal, but not anything to go crazy over. If you're looking for lots to eat, hit a buffet. If you have a group of adults and want to have a nice, classy meal, look into California Grill, Narcoosee's, or dig deep in those pockets and head to Victoria and Albert's.
Hope this really long post helps!
