I go every year because it's my local show, but it seems to hold it's own nationally. If you're in the region, CA or IL are the next closest and they are 8+ hours away.
I missed it last time, but I'll be going this year. Probably just for a day, either Friday or Saturday depending on what days my homeboys are gonna be there.
I've never heard of it, which is why I haven't talked about it. OTOH, Pinburgh 2011 was AWESOME!!! Best tournament/pinball event I've ever attended; liked it better than PAPA even. (The NW Pinball Show in Seattle this June sounds excellent with a great speaker list. But for competition or just playing pinball, Pinburgh is #1 by far.)
For cash payouts, I'm pretty sure Seattle show pays the most. You can pay for your whole trip for you a buddie or girlfriend if you win the Northwest Pinball Championships.