A bit late but my take - technically the film is brilliant, but no brilliance in the story, thought there is emotion. Expected more from a film which had Aamir, but the movie wasn't as good as the first part. It doesn't sound right, to take revenge on innocent people (bank customers) for a personal tragedy.
Aamir Khan has evolved into a mature actor cum producer who puts a lot of thought and prep into his movies. Known to be a method actor, he brings a lot of seriousness to any role/project, and is widely respected for that. But good boys hardly have fun - and so, he seems to have decided to play the antagonist in Dhoom 3. And boy, does he have fun!
Aamir and his pointy ears dominate proceedings completely in Dhoom 3, and you will definitely not complain that everyone else is side-tracked. We mention the pointy ears because we don't remember them being so pointy earlier. So much so....