I haven't been to Unum's for more than a cocktail in a few years. At that time, they seemed to go through a new chef every 6 months, so you never knew what to expect. Luckily, their bar staff was consistent, and the drinks stayed well made.
Sorry I'm not of more help. I have thought about going back, but I so enjoy the food and atmosphere at both Surf and MT's Local, that I haven't made a return trip to Unum's.
I've only been once, it was a "do not repeat" kind of experience. Can't imagine going there for an anniversary or any special occasion.
The Buckley restaurants, or Saffron Bistro would be my picks if it had to be Nashua.
I've been 3 or 4 times...the latest for a company Christmas party. Each time the food was good. Not amazing, but good. It's not a place I'd rush back to, but I wouldn't avoid it either.