I bought one of these to hold documents that I refer to frequently thinking it would hold up well. It has so far and it gets tossed around the office often.
The rubber spine has proven to be very durable. The ring assembly however is far less substantial and results in premature failure of the binder. Another minor annoyance is that the front view window tends to tear easily.
I use these on a daily basis. Probably open up the rings 20 times a day. Although they are a little more expensive they are completely worth it! They last me a year with much use!