Jealous you got one as a gift! How significant was the transition/upgrade? Radeongate can definitely be scary.
Wasn't significant at all, I just restored the rMBP with a Time Machine backup and continued using it like normal
The only noticeable difference is the much better screen when indoors, and much worse glare when outdoors.
Graphics performance was a huge jump (from 1GB 6750M to 2GB GT750M), and I can play BF4 at around 45-50fps with a mix of high and ultra settings, FXAA and 16xAF, 1680x1050. It can easily shoot into around 60fps in quite a few situations in BF4.
Otherwise, it's all but identical in everything else