I flew there in a 172 from Canada in 2000. It's a personal thing, but I'd say you'd have to be fairly keen on racing (autosport or something) to really get into it.
It's very impressive though, especially since you can see the entire course from the stand (Be sure to pay extra for the special reserved seats, take an icom or similar, and plenty of sun cream). Before I went, I'd imagined that they'd take off, dissapear over the horizon and re-appear at the finish line 20 mins later.
I especially liked the fact that most unlimited competitors have some British content, be it Sea Fury airframe or Merlin/Griffon engine.
You can buy a pit pass and actually talk to competitors, so technically it can be quite interesting. For me, the flight there, Mt Ranier, the Pacific cascades, Crater Lake, Oregon's central desert, etc etc was much more interesting than the event itself. But if you've never actually seen a forced landing, this is the place to be!