-Spoilers Are Minor-
It's not that bad, I promise. I never watched the television series, nor did I know any of S-Club 7's music before watching this movie, so I am speaking from a completely fresh point of view. Now, I've read the reviews here and most people are bashing this movie without the slightest hint of reservation, but I feel differently towards it.
Don't get me wrong, this movie is not 'good' by any stretch of the imagination, but for what it is, I found it to be enjoyable. You cannot expect too much from a movie about a pop-rock band being cloned by an evil master-mind, whom they fight simply through the power of their teamwork and their music. However, if this type or music is something you like, then chances are if you go into this movie with an open mind you will like it also.
The acting may not be the very best, but it is at least passable. The plot is ludicrous and definitely laughable, but as it is not attempted to be played seriously, that makes it all the more watchable. The music is fun and rather good for it's intended genre, and audience, the humour can be somewhat childish yet it still finds it's way to amusing. The sets and directing are certainly not going to win any awards but they aren't horrendous either. I am able to look at all above aspects objectively and understand why so many people don't like this movie, but it isn't a bad film for young teenagers, or someone nostalgic for the nineties and early 2000's such as myself.
All and all, six out of ten stars: watchable, entertaining, and not as abominably bad as it's made out to be.