If you're going to sit in the upper levels of this arena (300s, stay in the first few rows like A thru D. You get too high and you run the risk of having an obstructed seat.

No need to worry, the championship banners are on the opposite side of the arena so they will not block your view in 311 (upper corner of the arena).
The chairs have an almost fold out feel to them. The seating in the entire arena is almost just as bad. If you have ever been to Madison Square Garden, TD Garden or the First Niagara Center, they are head and shoulders above this venue.
But Islanders fans love it, they're the ones that have to sit here 40+ nights a year.