One of the not so great films (and the second one) is Ben 10: Alien Swarm. I don't know why they used the numeral "10". I think "Ben Ten" would have looked cooler (he's a Tennyson, if you don't already know).
The animation was good but the bad directing made it worthless. The soundtrack was so so, not as good as the animation and the acting was clearly forced and very childish. Let me explain that a little bit while still trying to keep this a short review: they rushed it, they give to many explanations, they make too many facial expressions and very childish ones, they act like kids (Ben should have been younger) when they actually look more like young adults (for example, they keep bragging about their rides, tech, girlfriends and all sorts of other "coolness").
That's it. 5/10.