FI and I stayed at the CBR December of 99 and 01. (he proposed to me there in 01!) This is the only resort I've stayed at, but I loved it during the holidays. (we weren't there DURING Xmas, but the second week of Dec...)
It's beautifully decorated in muted Christmas colors - no glaring red/green/gold theme...it's a subtle pink, sage green, pale yellow theme. Pontsiettas (sp?) all over the place, holiday music (with a carribean twist) playing in the background.
The main places you'll see the decorations is the 'check in place' (i'm sorry - I forget the name of the building) and Old Port Royale - the food court. The pool areas/beaches/rooms are basically decoration free, but you do feel like you are in a tropical location...not just Florida!
The ONLY thing I'd reccomend to you, is to get a room that isn't very far away from the food court...the internal buses are a pain and it's a far walk from some of the outer "islands" (The whole resort is split up into Islands - Martinique, Trinidad, S. Trindad - it's a hike from that one - and a bunch of other ones.) Make sure you ask a CM for a relatively close one. Yes the walk along the water is nice after a full meal...but some don't like it.
IF you have any other ?'s, let me know! Good luck!
(we're honeymooning at the WL...can't wait!)