Will killed any chance of me seeing it in 3D when I saw him on Letterman. Converted 3D isn't nearly as good as something filmed with the right equipment. Avatar had really good 3D. The Avengers, did not.
As far as MIB3 is concerned. I liked it. The second half more so than the first. Some scenes were really well done. Josh Brolin did a great job. The jokes weren't great though. Especially when I think about how funny the first film was.
It was a decent movie. A hell of a lot better than MIB2 (which wasn't hard), but I think they could probably end the series here. I can't see TLJ doing another one.