Possible spoilers.
Although there was some good acting - particularly Chloe Sevigny, and Radha Mitchell in the comedy half - this simply was not an engaging film. The segues between the comedy part and the tragedy part were awkward or sometimes not obvious. This viewer was initially confused by the fact that the supporting cast differs in the two halves; I thought with the way things were laid out in the opening scene that the people surrounding Melinda would be the same people, just reacting differently (more of a "He Said, She Said" premise). However, what we have is two totally different stories and two totally different women, both of whom happen to be played by Radha Mitchell.
The two playwrights in the opening scene - the comedian and the tragedian - supposedly take the same premise and go from there, but the two stories are only tenuously related. They do little to support the topic of discussion, which is that almost anything can be looked at as either comedy or tragedy. Nice cast, but a disappointing film.