If you liked the gunplay of Halo 4, liked things like legendary BR's or Halo 4 without the superfluous extras, you'd like H2A. I love playing it. It's exactly what I wish Halo 4 was.
Movement and strafe a bit slower than I like, and aim assist a bit too high, and dual wielding means needler and pistol are garbo, but if I had Halo 2 Anniversary with full 20+ remastered maps, I would never have wanted to buy Halo 5.
What they also could have done with Halo 2 Anniversary is a best of collection of maps. The best of CE, 2, 3 and Halo 4, ie. 3 small/mid maps and 1-2 BTB maps from each game. Halo 2 game play would have worked well on all maps (Halo 4 maps would have been a bit tougher since they were made to accommodate sprint or jetpack).