I'm not running it right now but I had the same question when I had a CRX. This is what I was told/ what I read about it.
The biggest pros are obviously the 110 octane, and that it burns colder than regular gas.
The cons are its inconsistency, decreased fuel economy, and the amount of work that goes into converting a car to it (the lines, a piggyback controller and/or an extensive tune.)
I'm not by any means an expert on E85 this is just the info I got.