I love the boosted experience (EXP) gain, but hate the disobedience factor and the locking of the rename feature. If I can breed the traded Pokemon in question, then that's what I'll do. Or I'll specify the preferred nickname in advance. I still dislike it when the Original Trainer is different in the summary screen, though.
Version mascots are a toughie to get with decent nicknames and such, which is one reason I prefer to wait for third versions now. I can get all three version mascots in one game, rather than having to receive some Groudon that was stupidly named AAAAAAAAAA.