I'm an avid Yankee fan that has already been to 50+ games since New Yankee Stadium opened. I love it here, it's my second home. I've sat everywhere except for the Champions and Legends seats aka the closest seats encircling the field.
I've sat in 434B twice for games, most recently for a Yankees/Tampa Bay Rays game. Tickets will run you about $20-$25 per ticket so it's a great way to check out the new ballpark without completely breaking the bank. All of the seats are individual seats; much more comfortable alternative to the bleachers. Our seats were on the outer edge of the stadium; not where you want to sit if you or your party are afraid of heights.

The well manicured grass is beautiful from up there. All of the players look like ants and it's easy to feel disconnected from the game. But the fan atmosphere helps you easily forget how good or bad your seats are. The smell of the Italian sausages and stale beer, the crack of the bat, it's like heaven, Not Iowa.