How does Unity Pro stack up against other game engines like Dice and Unreal? Other than the price and licensing etc. I mean in terms of capabilities, pro's and cons, differences.
Unity is better than Unreal I'd say.
Unreal is a hassel really, it's not as compatible with the softwares availible, and isn't as easy to learn. If you look at Unreal, you don't have to code as much, but their is a lot of random and usually useless items to change and tweak. Unity makes you code your own scripts (Atleast for a decent quality game).
However, Unreal does have an AI system, so if you're aiming towards a single player game with complicated AI, then Unreal would be best, and until Unity releases an AI system, it wont be the best in my opinion. However, as more people use it, more professionals get interested, more plugins/tools will be availible.
As for learning, Unity is by far easier to learn.
I can't say anything about DICE, never used...