I think that virtuals should have been brought back like they were, same icon, review process, and cache page layout. I think that there are more lame challenges now than there were lame virtuals back then.
I am not going to do Challenges because there will be a separate pocket query for them. I wish they were just a different cache type because I like getting everything downloaded in one query.
The last thing I would change is to get rid of the world-wide challenges. These are pretty much just locationless caches making a comeback. "Kiss a Frog" was a horrible first worldwide challenge.