Believe it or not, this game was a pretty much a first for me. While it is really the fourth game I made (Game boy Hero I & II were rhythm games, and I'm pretty much done with a board game that I haven't published yet), this was my first platformer, my first time working with large scale animation, my first time creating actual backgrounds (and designing them for parallax scrolling), and my first time making sprites that weren't just 16x16 people.
As for the art, the mixed styles wasn't really intentional, it just sort of happened. I actually was a little concerned about the inconsistency of it all, but it all did a great job of telling the story and came out great so I just ran with it. I never really thought about it, but yes, it does lend itself to a bootleg kind of feel which I think is pretty appropriate for a game whose whole concept was pretty much a joke to me. But while I made it as a sort of joke, at the same time I do feel that it is a fitting tribute to Warren Zevon and that he'd probably have a good laugh at it if he were still alive today.
Anyways, I'm really glad you like it. I'm currently working on another game for a different jam that will follow in similar footsteps.