Definitely mixed feelings about this. On the one hand, for what it is - a romantic comedy about a man with (undiagnosed) Asperger Syndrome and his project to find the perfect mate - it's very well written. It's fun, at times funny, and romantic in places.
On the other hand, it often feels like Don's autism is used solely as a vehicle for comedy. And, while I'm not an expert in the subject, I question some of the information shared. Don feels the need to follow a strict routine; any deviation from the schedule causes him extreme discomfort (typical among those with autism). But the author implies that, with just a little effort, schedules and routines can be broken without any lasting repercussions. From my (limited) knowledge of Asperger's, I doubt that's the case.
It seems that Simsion had an opportunity here to tell a funny, engaging story, while at the same time giving factual information about autism; it appears (at least to me) that he didn't manage to do that.