In http://arxiv.org/abs/1602.03840 we describe the various parameters that we were able to measure for this signal, and in http://arxiv.org/abs/1602.03841 we compare the results to the predictions from general relativity.

In Figs 6 and 7 of the second paper you can see the constraints from GW150914 on what are known as the "post-Newtonian" expansion terms of Newtonian gravity. Previously, terms beyond first order were only loosed bound, mostly from observations of the Double Pulsar system J0737-3039.

Just from this one event, we can also constrain the mass of the graviton to an order of magnitude less than the previous best measurement.