The journey the character goes on is perhaps inevitable - the film can only really end in either of two ways - but the way it gets there and the routes it chooses to take feels entirely believable and not just like its treading old ground. Even the compulsory love interest side plot doesn't feel tired or contrived but fits in with the story very naturally. It really does take you on an effective and affecting emotional journey, allowing us to travel the ups and downs alongside Adam in a wholly realistic fashion.
The fact that the script is written by Reiser who himself went through a very similar situation as the main character gives the film real dramatic weight and a ring of authenticity. But that also carries through to the writing itself which is top notch, moving effortlessly back and forth between drama and comedy - a perfect example of how to pull that off. What could have been a severely misjudged attempt at treading fresh comedy ground ends up being a genuinely touching, funny and often powerful tale that feels as personal as it does universal.