Amy really should have taken on a co-writer. Transitioning from a 15 minute stand-up routine to a full feature film is tough and it is common for comedians to fail. You will see many articles on Buzzfeed and other SJW blogs claiming Trainwreck as a success but they are just trying to push an agenda. Remember, no major studio will green-light a movie starring Whitney Cummings, Sarah Silverman or Chelsea Handler so they desperately want to claim this movie (directed by Judd Appatow with a supporting cast of male athletes) as a victory for women in Hollywood. While the studio will make a profit on this, I highly doubt she will be cast as a lead in a movie she didn't write or in a non "Amy" role. The studio has banked on Amy's loyal followers, Judd Appatows directing style and a ton of cameo's to fill theater seats.
The only guy she keeps as a regular FWB is the vain popping John Cena. While John Cena's performance is decent, his character is completely unnecessary. Even though it is plausible for Amy Schummer to get dicked by good looking guys (Yes the thirst is real), it is completely unbelievable for guys like that to want a relationship with her, let alone wife her up. They did hint at him being a closet case but the whole "guys who work out are obviously gay" cliche has been done to death and just isn't funny anymore.
Besides bad character development the script lacked structure. It felt like the first part of the film was an entirely different storyline. There were characters that felt were added later. For instance, Amy had a friend at the office who was introduced early in the film, but she only had 3 scenes in the entire movie and 2 of them were given away in the trailer.
Even though the message might be construed as positive, it is lost in an unstructured plot with no consequences. Let's compare Trainwreck to Bridesmaids. Very similar starts, Kristin Wiig's character was, like Amy, just "having fun" and then eventually takes risk and cleans her life up.
Amy's character also embarks on a similar journey but the difference is Wiig's character ends up with a cop after getting tired of being "fuckbudy #3" for Jon Hamm, while Amy's character turns down better dick than Jon Hamm and then finally settles for tall, rich, NY Knick's doctor.
This is why "Bridesmaids" will be watched 10 years from now and probably be shown in Film Genre classes while "Trainwreck" will be forgotten after its Netflix release.