I thought Grey was very good in this. I honestly do not understand why people thought her acting was bad. Her performance was so natural and conversational that all lines delivered by other actors seemed overly forceful and theatrical.
I recommend the alternate cut, available on the DVD. By removing the ongoing discussion amongst the airplane passengers, Soderbergh makes the relationship between Christine and her boyfriend much more direct. The focus - as voices drift over static, often blurred images of empty, expensive apartments - creates something almost hypnotic, if not genuinely suffocating; the entire film becoming a blue note of despair.
May be THE GIRLFRIEND EXPERIENCE is too meta for its own good, but it's more than mere novelty. Example: Soderbergh casts real-life film critic Glenn Kenny in the role of an escort critic. He does the same with New York staff writer Mark Jacobson who plays a journalist gunning for a profile on high-end escort Chelsea (Sasha Grey, ex porn star). And yet Soderbergh's style never overpowers his intent or sardonic humor