These binders are (so far) wonderful. I have ruined so many from constant use that I decided to give these a try - flexible bend points stand up to a lot of stress and keep going. Lots of good colors (but oddly no green). The only downside is they are a little more expensive so watch for sales.
The exterior and hinges of this binder are really tough and durable. The D-rings are good but give up long before the exterior is worn. The rings open easily but get deformed and don't meet all the way or overlap after hard daily usage. If you are careful this can last a long time.