If you've never played the Wii (or many other console games) before and you play this game, you'll probably like it, once you get the hang of the controls, because it's quite good fun, there's lots of things to smash and the environment is almost completely interactive. You can also mess around between missions, climbing around on buildings etc a la GTA but this novelty wears off pretty quickly.
However, if you're a regular gamer who also plays games on other platforms, this game is distinctly average. Graphics are ok, but seen far better. Longevity is non-existent. Storyline is dull and you really don't care about it. The controls aren't too hard to master, I didn't think, but even still they require more effort than should be required of what is essentially a run-around-smashing-things-up game.
The most important thing for me is that it's definitely not worth £40 or even £30, like so many games on the Wii. I got it for £25 and feel a little aggreived. Also, I reached the last mission as the Autobots, got bored and haven't played it since. That should tell you all you need to know about this game really.