Sat here for the May 11th matchup against the Seattle Mariners last season. It was Kuroda vs. King Felix, a game I couldn't miss. Was disappointed to see that the ballpark wasn't sold out that evening but I think the true Yankees fans have been priced out of attending games. This was even a problem during the inaugural season in 2009.
Could see the field fine but 414 is nothing to write home about, it's still pretty far from the field. It's right where the infield dirt meets the outfield. We were in the shade most of the time but it was an evening game so the sun didn't stick around too long. There is a Nathan's Famous Hot Dogs stand just outside of these seats which makes grabbing a dog extremely convenient.

P.s. - If you want to check out the famous Monument Park in center field, you will have to get to the ballpark pretty much as soon as the gates open which is two hours before the game. The line to see it will be ridiculously long.