I took my brother to his first Seahawks game for his birthday, 121 - row N, for the game against the Washington Redskins in 2011. We had a blast and enjoyed our seats. The only thing I would recommend is buying your seats in rows A thru Z. If you sit in the double lettered rows, there is a chance that you will miss some of the plays in the back of the endzone because of all of the fans standing in the first portion of the section.
I know this because I was watching a small bit of the game from up top as I was walking to the concourse to get another beer.
The sight lines are what you will find in the end zones of any football stadium. Good but not great. Still beats any seat in the 300s though. People always say there isn't a bad seat in a stadium or arena and we all know that is never true. Some seats are just better than others.