When I first saw this saw back in the middle of my 6th grade year I didn't know what to expect. A story-driven comedy adventure airing on Nick? Surprisingly though it works really well. While there are some "childish" moments there is indeed a very interesting plot through each of the 3 seasons (I haven't finished the third season so I can't really say.. I stopped following after my 7th grade year with Season 2) Of the approximate 60 episodes per season each totaling at about 11 minutes per episode there is just enough to push each plot and to leave the viewer coming back the next day with even more questions.
Upon re-watching it, a few things I must mention to an older, 17+ audience: The characters, while starting a bit obnoxious, really come into their own as the series continues and the drama rises. The acting is... meh. Some are decent actors but a lot of them wear the British twang a bit too much (Patricia specifically) which leads to some borderline "Whine" like performances and line delivery.
The comedy is usually childish with some annoying noises and characters acting silly... but as the series goes on and you learn more about the characters the jokes go from slapstick "meh" fest to really funny character jabs. (One of my favorites is when the make fun of Victor in season 2)
The show really becomes second nature and I have many fond memories of Season 2's middle being EXCELLENT. The plot in the first two seasons are convoluted to a point where it becomes a Joy (pun not intended) to watch unfold and how many ties the different strings of the mysteries really have.
Overall, give this show a shot.. like what you see? (The sometimes corny-British heavy mystery serialized show) Then defiantly check out Season 2.