s1 was brilliant. The whole season. Awesome.
s2 was good as well and a little more light hearted than the first season.
The problem with s3 is that me and my sister totally adored Rose, so we never accepted the new girl.
We were sobbing wrecks during the last episode of s2. I think that was almost like the end for us there. It felt like a series ending, because when there's only 2 main characters and you lose one then it just becomes something totally different.

I'm curious though so I still watched. I couldn't help myself :P