About two months ago, I booked TOL-DTW-AMS-BCN and back. At the time of booking, the NW agent asked if the name on my passport matched the name on my WP account. I said no, because I don't use my given first name-- "Paul" is my middle name. The agent advised me to update my WP account to match my passport name, so I did. I didn't have any trouble with passport control or customs on my trip, which is always good.

On the other hand, I didn't get mileage credit for the trip, nor for a quick SAN-LAX-DTW I booked and flew right before I went to BCN. I used TTU to submit a mileage credit request, and now the flights show up as "code 5". I sent another TTU and was told that the name on my WP account and the name on my WP *profile* don't match, so now I have to change the name on my account to match the name on my profile and ask, again, for the miles to be credited. This seems like quite a bit of extra hassle, so consider this a heads-up if you're in a similar situation.