Oh hai everyone. I started playing again now that school is over, and I figured I'd share some initial impressions of the metagame so far.
Sun: I admit that I ran a team tailored to deal with sun after reading all the hoopla about it, so that might have some influence over my opinion, but I found them very very easy to deal with. There are a couple of Pokemon that outright counter almost the entire playstyle (I used defensive DD altaria with cloud nine...yeah), and in general infinite sun isn't that difficult to deal with simply because it's either going to give a power boost (to the fire members) or a speed boost (to the grass members), not both. You might say "but charizard!", but seriously, just get your fucking rocks down and charizard ceases to be an issue because it can no longer come in on anything without immediately dying to residual damage and solar power.
Sun was difficult to deal with at times, particularly when I let a grass-type member set up, but I can honestly say that I had more difficulty dealing with 4th gen rain at the height of its power than I do with sun right now.
Hail: Hail in 5th gen is almost exactly the same as 4th gen hail, except instead of a dead weight pokemon they now have a mediocre pokemon to set up hail. Oh and I guess they have access to a 660 BST dragon...uh....okay so maybe it's a little different. But seriously, Kyurem was the only difficult part of dealing with hail teams, and it wasn't THAT bad - I had Cobalion on my team, a reliable stealth rock user, and priority, so I was able to deal with it sufficiently well. I'd be open to suggestions that it is broken though, simply because that Draco Meteor is just absurd if you don't have any steel types.
Victini: I didn't run into this little thing outside sun very much, but its sheer power both inside and outside sun is concerning. I actually switched Arcanine's ability to Flash Fire just for Victini, because even with Intimidate it was 2hkoing me after rocks -___- It also has excellent stats to abuse with its signature move, and decent coverage options. At least we probably don't have to worry about this since it's going to OU anyway.
Jynx: Jynx sucks ;__; Wait, actually it could be really good in hail! Why aren't you guys using jynx!
Metagame in general: I am really enjoying myself with this metagame. It's really interesting to see previously top OU threats mixing it up with old UU veterans and all these new faces. I've taken a particular liking to Suicune and Cobalion especially, and I have feeling that UU will be oriented around bulky, resistance-based offense once again.
Oh, in case anyone was wondering, my team is Celebi (offensive SR lead)/Cobalion (bulky SD)/Suicune (crocune)/Hitmontop (techtop)/Arcanine (CB Arcanine)/Altaria (bulky DD)