These days there seem to be a lot of shows about teenagers - or even younger kids(!) - "saving the world" and I find Totally Spies one of the most watchable ones.
The show has a sense of humour and the three girls are pretty much like what teenager girls should be - competing for boys and complaining about frogs' inside.
However, you need to bear with the villains in this series, because they are often rather corny, and not in a funny way.
Another problem of the show is it's often missing any simple logic (fighting on the top of a PLANE, "secret spies" making themselves seen on TV, etc.)
Also, the episodes don't differ that much from each other. If you've seen one episode, you've seen them all - or at least most.
All in all, I do think this show is somewhat entertaining if you are bored but truth is, there are many better stories out there.