It improves. I'm not the best salesman for it. Most honest fans will tell you the show is flawed. It's monster of the week for most of season 1. The creature stories get better in season 2 and the overall plot starts getting more interesting around season 3.

Season 4-5 are considered the best. Season 7 it starts dunking on itself and it's premise, and becomes more cheesy but with a lot of found-family/parental trauma motifs (everyone in supernatural has beef with their family.)