As good as it gets. :)
Hulk Vs. (2009) is exactly what I want from these animated movies. I've got both Ultimate Avengers movies, and I rented but so far have not bought Iron Man. This is in another league. For this Hulk fan, it's pure joy.
I love that that both movies are fully their own movie, with their own music (great music!) and different types of opening credits and atmospheres.
I love the voice acting. At "worst" it's good (Thor) and mostly it's sublime (the Hulk, Wolverine, Deadpool). I don't see a lot of room for someone else to come along later and do a better, more emotional, more authentic, more varied and interesting Hulk voice, ever.
The stories are good, the backgrounds are appropriate, the fighting is ample and top quality...
Even the extras, the commentary tracks and the "making of"s are good. Nothing that I could fairly ask for has been neglected.