My friend and I sat in row 11 for the Wildcard game vs. the Colts last season. We usually sit on the lower level for games but for a playoff game, we just couldn't swing the steep ticket prices so we settled on these seats. I had sat upper level for other Ravens games in the past and I must say, I'm not a fan. Just too far from everything but for the Playoffs, we didn't mind as much. 551 was only a few sections away from those that sit at midfield (20 yd. line) so you should get a good view from virtually every seat. I would avoid any seat past row 15, having that many steps to climb just makes it too difficult to get to the bathrooms and concession lines - a sure bet that you'll be missing some of the game.
The leg room has never really been a problem. As cold as it was that night, we were actually relieved to be huddled together with so many other fans.
The one major downside to holding upper level tickets is the climb to the top you have to make via the ramps. There are ZERO escalators to take fans to the upper level. On the club ticket holders get to use the escalators (not surprised). So you'll want to use the ramp on the west side of the stadium near Gate A (Hamburg Street) to reach section 551 the quickest way possible. The walk takes longer than you're likely anticipating, so make sure you leave the tailgate in plenty of time to make it through security (which has tightened) and to your seats.
If you're old enough to be a fan of the old Baltimore Colts, you might also like to know that there is a statue of Johnny Unitas outside of the North entrance. It's a great spot for photos. The Babe Ruth museum near Camden Yards is also a neat stop for fans coming into town. And of course, as always, be sure to visit the Inner Harbor.