Nowadays, I see a lot of downsides. First, it's a full-time on site job, which is something I left behind almost 10 years ago, so it'd be tough to go back. Probably more importantly, I doubt they could offer me the kind of salary that would tempt me away from consulting.
At this point, the only reason I could see myself working for a big company again would be if one of my products made it onto their radar and I found myself acqu-hired. Even then, I'd probably look at it as a necessary evil that came with a nice payday. Given all the stories of founders getting absorbed by the Googles of the world, waiting out their obligatory 2 years, then jumping ship, it just doesn't seem like a good fit for somebody with an entrepreneurial mindset.