MIB: Alien Crisis is what it is. For about $5 it is probably worth the simple gameplay and kind of fun story, but much more is a stretch. You can actually use your Top Shot Elite with it if you have one, that never seems to get mentioned/wasn't really publicized.
I for one was severely disappointed in Halo Anniversary though. I had never played the first Halo, was surprised to find out how boring and lack luster it was.