Not great at all. Very disappointing, even for someone who just liked, as opposed to loved, the first film.
Even as a comic adventure, it's hard to look past it's overly stupid moments, and bar one or two exceptions the majority of the jokes are stretched way to thin or fall flat.
Certainly think it's one that kids will love, but personally found it tedious and tiresome with the relentless CGI ending up just a dressing for a story lacking in substance and content. Had heard of the multiple mid credits beforehand, but could only be bothered to stay for a couple or so which kind of says it all.
The saturation point of Marvel Studios' output doesn't help in many ways, whereby the first one worked as a one off surprise, the depreciating quality of the films in general just works against this particular effort.
Not trying to put people off, as I'm sure there was plenty of satisfied customers the other night, but just cannot get past the blandness of this one.