There is a lot that Salamence going for it, and against it. Yes, it hits like a tank, yes it's unpredictable, but it's not the only pokemon in OU to do so. Personally, I wouldn't mind seeing Salamence leave OU, it is a pokemon that is hard to switch into, but thanks to the few common recurring battle conditions, Salamence can't stay in for too long, you MUST factor in 25% Stealth Rock, 6% Sandstorm damage, 10% Life Orb damage (if it has it) and then damage it takes on the switch in (if this also applies), so you are looking at 31% (at least) on the switch alone (25% if Salamence comes in after a pokemon has fainted). It will also take 6% + 10% each turn assuming it 1. Stays in and 2. has Life Orb, it all adds up really quickly.
Another thing is that Salamence, unlike Garchomp, cannot utilise Yache Berry quite so well because there is a lack of bulk on the special side and will usually take 31% damage on switch-ins. I am not saying Salamence can't take a hit, it has a small amount of bulk, just not in comparison to the likes of Dragonite or Garchomp.
If you flip the arguement over, you have the fact that it can usually 2HKO everything with 1 DD, and would need a Scarfer or Scizor (or other strong priority) to be able to take it down, or there is the Mix set which hits both sides of the spectrum pretty damned hard. I believe its movepool isn't god awful, but it's not amazing, when you think MixMence, you think: Draco Meteor, Earthquake, Fire Blast, Outrage, or on the DD Set: Dragon Dance, Outrage/Dragon Claw, Earthquake, Fire Blast/Fire Fang. You can see the recurring type coverage here (yes I am aware that it can hit everything in the game for neutral or more). In this respect, it's predictable.
Personally, I am not convinced it is Uber material, but I wouldn't mind seeing it get tested. IF I had to say it were uber under any category at all, it would have to be the Offensive Characteristic, but thats only if I thought it was Uber material, and I'm not sure it even fits that.