Hannah Montana (both the show and her music) are irritainment for me. In case you're not familiar with the term, irritainment is entertainment that is both irritating and entertaining at the same time. The term was originally coined to describe "Who Wants to be a Millionaire".
I don't like season 1 as much as seasons 2 & 3. I also find Hannah Montana's music from season 3 more entertaining. Plus some of the songs on Miley's "Breakout" album. That said, I would never buy any of her music or put it on my computer.
It's more of a guilty pleasure thing really. I know I shouldn't get any enjoyment from it, but I do. A lot of the time when I watch it, I'm thinking "god this is terrible", but still find it funny enough to keep watching.