Drove down from Boston to see my Bruins take on the Islanders. 319, row c.
Nassau Coliseum is not the best I have been to, but it is nowhere near close to the worst arena that I have seen either. Among the NHL arenas, it is definitely below par. It reminds me more of a large college arena rather than an NHL arena. The seating was pretty good and my view was never obstructed, but keep in mind I was the third row. The tickets for those seats were dirt cheap compared to what I would have to pay for Balcony Seats at the TD Garden in Boston, which is a huge plus.
The mezzanine isn't bad for games, just sit closer to the center line and you'll be fine and will have a great view of everything.