https://www.youtube.com/watch?v=HBsOmTglpkYA participant from this Battle Spot doubles (basically, vgc2015 ruleset) hosted by pokealex (6th WCS 2014 winner) reporting in.
To those saying that VGC 2015 will be cookie cutter I must state that thus far, the teams that made it to the semifinals were nothing like that.
The host and eventual winner, Pokealex, brought a TR team with Cress and Mega-Maw with support Arcanine and Hydreigon and Zapdos standing out.
Riopaser the follow-up brought a team with many interesting picks such as Hippowdon, Florges, and Rotom-Mow which got the job done for him.
3rd and 4th place (indistinct since there was no real placings) brought M-Gengar with Hitmontop, Whimsicott, Gardevoir, Talonflame and something else; and then me who brought a Mega-Swampert team.
My impressions of the meta is that while the 5th gen mons are really strong the updates have made adding more unique twists necessary as now elegant solutions to otherwise commonplace problems are possible.
Personally I felt the meta has changed enough to make it so that goodstuff teams with 4 legends, 1 pseudo and then a mega will have a harder time. If you lack a game plan and your opponent has one and has prepared in advance for what you're packing, you're in for a world of hurt. That is not to say gimmicks were successful (they never will), but only those teams that went a step beyond really made the cut.
As for speed, it's between VGC 2014 fast plays and VGC 2013's bulk. In my match between me and PokeAlex there were many trades of blows, but they were nearly always solved by the hard hitters in each other's team doing what they were good at and getting KOs in.
So with that said, enjoy the battles and hope they are of any help.