I'm very glad for the lack of power creep, but I do wish that Gen VI would have some more impact on the metagame. Well, perhaps 'impact on the metagame' is the wrong term. It feels like there isn't much beyond balance tweaks and 2 or 3 Pokemon/Evolutions who will probably end up Uber.
On one hand, we have nice balance changes, like the weather nerf, Fairy types, the weather nerf, the Steel nerf, the weather nerf, the decrease of base powers for some special moves, will-o-wisp buff to balance out the specal moves nerf, and - my favorite - the weather nerf.
On the other hand, some things have just gotten a little bit out of control. Mega Blaziken is basically a better version of something that was already Uber material, and the lack of power creep means it should probably stay where it is. Mega Gengar is another ridiculous thing, since Shadow Tag is just absurd. Hitting almost as hard as LO Gengar with more speed and enough bulk to not die to priority moves is simply way too good.
Both of these threats have their counters, of course, but the problem is that these counters are effectively the ONLY way to deal with these Pokemon, or are so niche that these Pokemon are the only reason you would use them in the first place. It would be a case of them over-centralizing the metagame. Teams will be forced to pack at least one Pursuit trapper to even hope of dealing with Mega Gengar (there's no many that can really deal with him, to be honest), and every team will also need something like Talonflame/Gliscor/Jellicent to deal with Blaziken. It's not that they don't have counters, just that if they are not successfully countered, they are nearly unstoppable. But I digress. Back on topic.
Aside from those two, Gen VI doesn't really have any new Pokemon that make an impact. Aegislash could do some incredible work, but I can see that Pokemon potentially getting chained into Ubers, where it would probably still do well. Either way, aside from Aegislash, the only Pokemon I see having a real impact is Mega Lucario. A couple of other Megas like TTar, Scizor and Garchomp will probably have a little time in the spotlight but are outclassed in many cases by their non-Mega forms. Mega Gardevoir and Mega Charizard X look useful, but Gardevoir has to deal with some rather weird stat distribution, and Charizard is still crippled by Stealth Rocks if he doesn't evolve early (although even that only mitigates the problem).
I like the balance tweaks, but as far as raw content goes, I feel like Gen 6 was more like Gen 5.5. If Mega Blaziken, Mega Gengar, and Aegislash don't end up Uber, that's a different story, but not THAT much of a different story.