Pro and Cons of E85

Pro;

High octane! Very high. Cheap price vs gasoline.

Con;

Octane as shown may not be all that. As mentioned quality is an issue. You can get testers to test the E-85 on the spot.
Availability. It is not everywhere you want it to be. You will have to know where it is before you go to a certain spot or route.
Less BTU return vs gasoline. This means you will need to use more fuel for the same distance traveled. Cruise or wide open throttle.

The secret (well, not really) is to run as high as a ratio as possible for the E-85 as so to try and off set the loss due to the lower BTU return.