More boost, less detonation - Pro
Worse gas mileage, all rubber seals in the fuel system have to be replaced with teflon - Con

It depends on how old the car is though. My 02 Eclipse ran E85 with zero issues. Everything was OEM, even though I used bigger injectors and a bigger fuel pump, both were just from different Mitsubishis.

I say its all in the tuning. With my big cam, heads, full exhaust and e85 Im getting 21mpg cruising on the hwy. Not the stock 28mpg I got stock but you gotta sacrifice something. If you really want power, youre not worrying about mileage.

Thats still not bad, thats about what I was getting.

You have to remember that you are using more fuel on Ethanol. I see about a 5MPG drop myself, running the 50/50 91/E85 mix. But I have HP tuners so I run one or the other. I believe its something like 30% less MPG on straight E85 (don't quote me on that cuz I amy not have it exact). But in all honesty, I usually run 91 for the commute and a few tanks here and there of the mix to have a little fun with. Nothin like roasting the tires from a 60mph roll to get the blood a flowin.

^^
Yup, 33% less mpg with 100% E85.

For those of you in the OC area that want to run E85, but couldn't, you can soon. http://propelfuels.com/ is converting a gas station here in Fullerton to E85 as I type this. I know what I'll be running when the Typhoon is put back together.

Do you know when it opens?

Not sure, nothing says when. They just have a huge hole in the ground right now.

This is excellent news. I would like to get some closer to me but this is a start.