This movie is, quite simply, fun. Fans of the hit series will be reminded of the smug attitude of Steed, although no one will be able to catch the magic between the original actors. However, the movie does well for what it is, and is quite enjoyable.
Unfortunately, it caters to a narrow range of people. Those who have never seen The Avengers might think the acting is bad or dialog poorly written. This is not the case. They are merely mimicking the style of the TV show.
Of the other hand, those who are fanatical fans will hate it because it's not as good as the TV show, and makes many changes.
But those who enjoy the show and aren't nitpicky will find this a thoroughly enjoyable movie.