The first season was a surprise, as I found it quite funny. I don't like singing in tv shows, but it was part of this show, so whatever. But the humor was often pretty good, Victoria Justice actually decent enough of an actress and funny.
Season 2 fell a bit flat. It started to wind out.
Season 3 and 4 were just mediocre. Characters became caricatures (as many shows do when they wind out), humor was less creative and every episode kind of felt like finding an excuse for them to sing. A couple episodes in the second half of season 4 might have been better actually, but nothing exceptional, and it was the end anyway.
So there was potential, not fully exploited.