I am only 21, so I saw this show on DVD, and despite being old and outdated and before my time (a little), this show is amazing and it seems like a basis for all teen dramas. In the early seasons, it is heavily focused on the Waslh Twins and their friends. It is also issue-based. While this is good in a way, the soap-opera aspects added from season 3+ became the reason I fell for this show.
The college years are absolutely my favourite. Brenda left, and Valerie replaced her. I was always at odds about the change because I prefer Brenda over Valerie, but Tiffani over Shannen. However, Clare became one of my favourite characters and the situations they went through in college were always my favourite. After season 7, the series began to go downhill. Noah is probably the reason - the guy can't act at all. This is the season where I started to hate Kelly - and I am a huge Jennie Garth fan. Donna losing her virginity was a jump-the-shark moment. Clare left, and Carly and Noah were inadequate replacements. This is the show I wouldn't reccommend to my friends or quote day after day, and OTH and GG will always be far superior, but I do adore this show (at least before season 9), and think that without it, the better teen dramas I love probably wouldn't have been created.