The first episode is brilliant. All the others are good too apart from the actual plots which are all really far-fetched and kind of pretentious. Some of the episodes did actually have a cool and interesting concept but the way they got executed just sucked. It's such a shame because everything else about it is really good, the plot just ruins it for me.
I never liked it that much, it's fun but it's just not for me I guess.
The best thing about Big Time Rush is that it knows what kind of show it is, I would've never been able to enjoy it as much(or not even at all) if it wasn't self conscious. It really was about time it ended though.
Both Hugh Laurie and Stephen Fry are great at writing comedy and have incredibly good comedic timing. These two work incredibly great together and it's such a shame they haven't done that much together since this and Blackadder.