Ack - I'm really sorry to say this, but it's losing me.
I loved the first three series, but I'm starting to feel a bit like the kids are too... self-aware, perhaps? It's not the kids' fault, they're just trying to the best job they can, and they're acting their little socks off, but that's almost precisely the problem. It can't be helped, but because they know what's up, it feels all a little too precise and premeditated. When Ben played with the toys I used to get the impression he was doing it 'cause the actor felt like playing with some toys. Now it looks like he's sucking up the keys 'cause the audience are gonna go "oooohhh!!"
Similarly, there was a little line towards the end - "it's got loads of dents in it. like someone's beaten it. with a hammer," where she described precisely what had been going on off-screen. The joke was a little bit laboured - "look, this is what happened!" - which I'm not criticising (the fantastic!) Ramona Marquez for, but it's a side-effect of knowing "this is where a joke goes" but not yet being a comedy expert.
It looks like the kids - as they inevitably would - get why they're funny, now, which has the unfortunate side-effect of making it feel less authentic. And the veneer of authenticity was what lifted it from being an okay sitcom into that sweet spot. Now it's back to being an okay sitcom again. Which is always welcome! I can think of much worse things to fill the half hour spot with. But it's not the best start to a series.