Good or bad is open for debate however I have been using it for years in various small engines; outboards and automobiles with no problems I can blame on ethanol. It does attract moisture so if your not going to use the engine for a period of time it's best to use an additive; this applies to all gasoline. It is also a cleansing agent so if you have an old engine that has never seen it and switch to ethanol it will loosen buildup in the fuel system causing problems. Below is a copy/paste from yamahaoutboards.com.

04. Are Yamaha engines compatible with E10 fuel?


All current models as well as most engines built since the late 1980’s have been designed with fuel system components that are tolerant to fresh fuel containing ethanol up to 10% (E10). Outboard fuel systems can still be affected by: water, dissolved gum, varnish, corrosion particles, and dissolved resins that E10 fuel has cleaned from the distribution system and your boat’s fuel tanks