I enjoyed The Rosie Project as a quick and light book, though it is a bit predictable. 
 The Wife Project reflects on how "scientific" methods for finding the perfect partner aren't worth much compare to shared experiences. 
 The Father Project is a wild goose chase. I wouldn't have wasted my time humoring someone I didn't know and would have tested a certain sample from the start. It is an excuse to put Don in new situations (bartending a party comes to mind) and for the characters to get to know each other, but it's clumsy. 
 The Rosie Project is disappointing. All those changes are a bit rushed and the reason for it doesn't seem worth it. Not my favorite part of the book. 
 The end is so full of other changes that it doesn't seem to fit the characters. 
 Also, am I the only one who thinks that proposing to someone you met less than six months ago is ludicrous? 
 I still think I'll read the second one, The Rosie Effect, but it has dropped several positions on my reading list.