How early you guessed which girl he would end up?

Real early. This movie really sucked bad. God, where do I begin? Even my GF hated it and she is a sucker for chick flicks.

I got it as soon as they met. That conversation at the copier gave it away for me.

Does he "end up with" the artsy girl, or is she just the only one of the three that he hasn't failed at a dating relationship with - yet.

The end of the film is not a "happily ever after", but a "moving on from the third failed relationship (two with the same woman) and starting a new relationship" thing.

Her story about looking for the book made it obvious to me.

I didn't know EXACTLY how it would pan out, but I guessed pretty early on that April was going to be the one he ended up with. They had this obvious instant connection and chemistry, were friends for a long time, and also the "definitely maybe" line she dropped early on, as others said. I thought that one of the other two would be the mother, but April would be the one he ended up with.

I actually guessed around the middle of the movie that Emily would end up being the mother, probably when she left the message on his machine saying she had moved to New York. Summer just never seemed like she was going to be it - the very first thing we saw of her was that she had made out with girls in college and was sleeping with an old man...gross. Also I didn't really see the chemistry between them at all - their relationship really didn't seem like anything special. I didn't see chemistry between him and Emily either, but they were college sweethearts, and I had a feeling that they were going to reconcile and get married - even though she wouldn't end up being his true love, because that was April.

RESPECT MY AUTHORITAH! - Eric Cartman

Depends on what you mean by "ended up". I pretty much summed up 20 minutes into the movie that he would "end up" with Isla. But I surely didn't guess the mother right.

I may be on the side of the angels. But do not think for a second that I am one of them.

Around the last 5 minutes :)

I guessed it from the opening credits. Isla Fisher was billed higher than the other two girls so I figured she would be the main love interest. However, I never thought she was the mother, since they made it obvious she was 'the one' throughout the movie and it wouldn't make sense for them to divorce.

I guessed Emily/Sarah was the mother about 20 minutes before the end. I earlier thought it was going to be Summer/Nathasha, but when she revealed she was pregnant I ruled her out.

I didn't think they would make Maya Will's stepfather.