Ahh, the curse of Jim Carrey.
I mean there's no-one quite like Mr C. Literally, there isn't.
Combine this uniqueness with his refusal to make any sequels now that he's a superstar, and the result is two-fold:
1. A heap of awesome, original Jim Carrey movies.
2. A heap of spin-offs that cryingly miss him.
This one doesn't even try.
In fact, this has to be the worst non-Carrey sequel I've seen. It's as if they just gave up before even starting, which for the reason outlined above I can hardly blame them for. Of the two actors donning the eponymous mask this time, neither has anything like the extremity of insanity that the original lead had.
The other two of the four mask-wearers here fare better, but mainly because they're both CGI, which works wonders for the number of facial expressions that are pulled. The baby is still a baby though, an identity which is always the death knell of any possibly of humour in any movie ever. (babies kill comedy, just as certainly as a harp on the soundtrack will) On the other hand, or paw, the dog is awesome, and really should have been given more screen time.
The generic mother never gets to wear the mask, and for this we can be grateful. The thought of the maternal one employing extreme cartoon violence to self-righteously punish Loki for stealing her baby just doesn't bear zzzing about.
Speaking of whom, I've never read a Dark Horse comic (I consider them to be an unknown competitor), but given the presence of Loki and Odin here - and indeed their name-checking of Thor - I decided to assume that this tied-into the current Marvel movie shared-universe.
After all, any film can be improved by adding a bit of Stan Lee.