First things first. Pacific Rim is complete rubbish. But it is so complete that it is actually quite wonderful. If you are prepared to make the mental effort to suspend your disbelief somewhere really high (or just leave the critical part of your brain at the door) then you will really, really enjoy it.
If you are able to take on-board “facts” like it requires two melded human brains to control a giant toy robot and that the best way to select pilots for said robots is to to have them try to hit each other with wooden sticks then you will do just fine.
The thing that did it for me was the level of detail and little cultural references that made the daftest parts make sense at the time. The acting is well up to par and everyone gets on with the job in hand with enormous gusto. The computer graphics guys had taken the sensible precaution of making sure that most of the action is either at night, in the rain, underwater or all three at once, so that everything looks properly believable and any necessary bending of the laws of physics is nicely hidden.
If you only go and see one big, daft, movie this summer then it has got to be this one.
I liked it so much I bought the book. Which is very good too.