Arcanine's arrival on this list is super surprising! I'm glad I've been breeding them lately, as his value is probably going to go up! I'm glad Crobat's in OU, because he is one of the top leads in the game, and he was frankly too powerful in the UU where he was late last year.
Deoxys-S and Wobbufett will be interesting. I haven't tested them out myself, but I'm one of the very few people who like Wobbufett, and I can safely say that I can't wait to try it against the non-uber pokemon for a change. It's probably the reason why Smeargle is on OU; a free turn to induce a switch and do a set-up move.
Electivire's use has went down, but I'm quite surprised that it got off the OU list. I didn't think his use went down that much, but however, with the next list in a few months, I could realistically see the gyrados/electivire combo be used more often (because of less people using Electivire at the moment), and get him back in OU.
Breloom's kinda a shocker too, but the reason he's going down in use is his low speed is making him an easy target to OHKO, and choice scarf users don't exactly help that cause either. If he doesn't go first, chances are, if you don't have a focus sash (which many brelooms don't have), he will die. Simple as that; no defenses with low speed. The metagame has caught-up to it and has made it a little less powerful.
For these pokemon who got demoted: Electivire, Breloom, Hippowdon, Dragonite, and the others, I think they will make a return to OU next time around. I've noticed that quite a few of the powerful pokemon that get demoted to BL do come back to OU, because people will assume its use will be low with it being on the BL list, and they will not have an effective counter against it. So you can complain about those pokemon being in BL for now, but that leads to two things:
1) That doesn't mean you can't use Dragonite and Hippowdon in most OU battles, since you can use any pokemon OU or lower if you wish. Plus, isn't bragging rights of not using any OU pokemon to beat an OU team pretty sweet? You now have better chances of that with Dragonite in your disposal.
2) If you really want those pokemon back in OU, use it on your team every chance you get and promote them to get back on this list without flamming other people. If others do the same, in a few months, they'll come back, and you all won't be complaining anymore of this changed list.