Watched all of this over the past month or so, finished up yesterday, so finally getting a read through this thread today.
Very, very good show, with an excellent ending. The quality did dip a good bit for me in the third season (mainly due to the severe hatred I had for Tuco's cousins and every scene they were involved in) but picked up again very quickly.
Walt has to be the most riveting and unpredictable (psychotic?) character I've ever seen. And Saul Goodman was immense too. Everything that involved him was great entertainment.
Overall I loved it. One of the best series I have watched.