The fun for me was always in seeing Adam and Jamie doing the actual research and building in order to test a myth. I liked being able to follow their thinking process. They would sometimes run into dead ends before even getting to the building stage, forcing them to rethink their approach. That gives a better picture of what science and engineering really is like, too. I suppose there's always been some scripting and editing, and the early seasons were flawed in other ways, but it definitely seemed to be a lot more genuine early on.
It's not about an entertainment tradeoff for me, as I simply don't find the current show format entertaining. But then, I guess I'm just not in the show's target audience anymore. I can accept that. Some good news, though, is that Adam and Jamie have started a website [1] where they (primarily Adam) show off builds and gadgets, without the shackles of the TV show format. For example, [2] is a video in which Adam Savage explains a tool stand for 14 minutes, which I honestly found more entertaining and interesting than any MythBusters episode I can remember seeing recently. I like seeing the nuts and bolts of their builds and experiments, quite literally.
I hope the final season ends on a high note. All things considered, it's been a good run, and the team behind MythBusters deserve a huge amount of credit for what they've done.
[1] http://www.tested.com/ [2] http://www.youtube.com/watch?v=TWQAYfGxsPE