I've been to the Bleacher Bar several times as I work near by. Its always just average, food ok, atomsphere just ok even though its in Fenway. This is more of tourist trap.
On my last visit I got the grilled cheese with bacon and it just tasted kind of bland. The server was very nice but overall it always seems stale in there. Yes they have a view of the field but you can't just sit there and enjoy a meal, they will cycle you out, plus that area where you can view the field (the whole gimic to the place) isn't that big. The restaurant has a weird shape (thin and long) to it so when its packed its hard to move around.
Basically I go there when I cycle through my 15 or so places to eat around work but I don't rush there. Its mostly a tourist draw.