This collection of three feature length animated films is excellent value. 'Ultimate Avengers' is a really good film based on 'The Ultimates' comic books and featuring most of the characters everyone is now familiar with - it's also got a couple of others thrown in there too. The storyline's fairly similar to the 2012 blockbuster, so don't expect huge differences in that regard. The follow-up continues the story and is somewhat inferior, but still well worth watching.
The bonus feature is in another league though: 'Next Avengers' is essentially aimed at children, but for my money it's a fantastic little film in any context and worth the price alone. It stars a unique group of 'children of the Avengers' characters, supported by one or two traditional heroes in an ever-so-slightly dark future and it never wastes a scene - superb! I must have watched it a dozen times and I'm 37! - Well, physically at least.