I think that there is a part in almost all of us that is at least somewhat interested--if not excited--at the idea of giant robots punching giant monsters, even if some of us would not totally care to admit it. The problem is getting this Transformers vs. Godzilla monsters concept done right. We all know how flawed the Transformers movies are, for example. The problem is getting a writer and director that is going to take such a premise remotely seriously and is not just going to try and appeal to the lowest common denominator with no regard for things like plot or script. Pacific Rim--directed by Guillermo del Toro--has succeeded in doing this right.
The premise is this: monsters called Kaiju come out of a dimensional portal at the bottom of the Pacific Ocean. (It makes more sense later on in the movie.) They start wrecking everything. So what does the world do? It "builds monsters of their own." Giant robots called Jaegers that can kill the monsters--either by punching them in the face or with some sort of specialized attack.
Now this is where things get weird--two people have to pilot these robots in tandem through some pretty confusing neural link. There is some nonsense about "drift compatibility" that is never properly explained--which is odd because they actually go to a few more lengths to explain things (such as the Kaiju race) than normal in a movie like this, but they never really explain what exactly drift compatibility really is or how it even works. But you tend to forget about that kind of thing once two people get those robots working and start fighting monsters with them.
As is to be expected, the action sequences--the robots vs. monsters fights--are totally awesome. The most memorable set piece is the battle in Hong Kong, which actually takes place from two different points of view. With the two points of view combined, this goes on for about 30 minutes--and one is never bored. Actually, one is almost never bored during the movie. After the title reveal (which oddly comes 15 minutes in), things are kind of slow for a little bit, but other than that things are pretty fast-paced throughout. The awesome action sequences and outstanding visuals (particularly near the very end) help with all of that.
But even the characters are decent enough. The main character Raleigh is a little dull, but Mako has a more interesting backstory. Idris Elba often kind of steals the screen in one of his more memorable performances, which includes a good speech near the end. Then there's the two scientist characters--they're a little annoying at first, but they get more amusing over time and their side plot to find out more about the Kaiju is interesting enough on its own--especially when one of them encounters Ron Perlman's character, who also kind of steals the screen when he's on it (even though he's not on it for very long). These characters are nothing outstanding, but they're good enough that aside from the bully-esque secondary antagonist of sorts, we almost never straight up dislike them or get bored by them.
Pacific Rim is a popcorn action movie, plain and simple. But it is also about as good as a film can get in that category, not unlike Independence Day. It's fun and exciting enough to keep us interested. The story quality isn't Christopher Nolan level, but it's just good enough. And it doesn't feed us a ton of ridiculous character interaction that is both super boring and totally irrelevant to the plot or anyone's story arc. (Are you listening, Michael Bay?) It's rare these days that such a movie of this caliber can get things right as much as it does. While some will definitely enjoy more it than others, I kind of feel bad for those who can find no room in their heart at all to enjoy this super fun movie.