The title says it all.
Hulk vs. is a mixed bag. In some ways, of all the Marvel direct-to-dvd animated films it has some of the best writing and production values as seen by the animation. In other ways it is a disappointment and still pales when compared to anything DC has put out. It is inaccurate to call this a feature length-film. Once credits are removed each is about as long as a half-our cartoon. The point of both is not the story, but the battle.
Hulk vs Wolverine is the better of the two shorts. The battle between the two puts in a good showing for both of them with the Hulk's brute strength vs Wolverine's speed. However, it starts to lag about halfway through with another pointless retelling of Wolverine's origin. Watching the Hulk casually destroy Weapon X members has some entertainment value, but ends right before it gets old because nothing can threaten him.
Hulk vs. Thor is the longer, but weaker of the segments. The writers try to give a bit more of a story, but fail to develop any of those story parts. Thor's weariness of battle is out of character. Worse, all the fights involving the Hulk are boring and get old fast. The Hulk with ease plows through armies of gods and frost giants that gets old fast. Worse, the much anticipated fight with Thor is a let down as Thor does not bother to fight back half the time. Unlike the Wolverine fight the Thor fight is so one-sided one quickly loses any interest unless you either hate Thor or want to see the Hulk bulldoze across Asgard. Loki's lackluster contribution towards the end shows the writers were going through the motions in the last few minuets. Unlike Hulk vs Wolverine that tried to show respect for fans of both characters Hulk vs Thor tries to promote the Hulk and Banner as either unstoppable for the former or a great hero for the latter at the cost of Thor and his entire world. All in all, it is plain boring.
In the end, worth renting to see once, but unless you are a die-hard Hulk fan or hate Thor then it is not worth buying.