A fun, action packed trailer made this movie look quite good, in a dumb sort of way. Sometimes there is nothing wrong with a dumb movie, I quite like the Transformers films and things like Independence Day and 2012. This however is inexcusably boring.
The first five minutes and the last five minutes are actually quite amusing, there are a few funny lines, and the supermarket break-in scene is almost like from a different movie, because it is genuinely funny. However the two hours in between are awfully scripted (honestly, some of the lines are so bad I just can't even bare to write them down), and the terrible script can't even be livened with some exciting battle scenes, because they are just so dull. You don't care about a single one of the characters, so there is no peril, it simply doesn't matter who lives or dies.
On the positive side, it's techically very well accomplished, there aren't a lot of faults with the effects work, though there really isn't anything original in the entire film. The old guys turning up to save the day is just laughable, and casting Rihanna instead of a proper actress is a good example of how poor the whole thing is.