I found the drastic shift in tone/realism to be extremely jarring. We went from total comic book fantasy to a rough attempt at realism, but it makes the continuity confusing... where are the super duper mecha suits? Why didn't we see their massive underground base? Was that destroyed by President Zartan?
I also found it weird the way this was basically a new cast of heroes without any explanation. So were all the other characters supposed to have been killed, then?
I enjoyed it, and I enjoyed the first one (in a silly way). The best sequence by far was the ninja mountain fight. All the other action scenes were just alright.