As many others have written, The Library is a great choice if you're in the historic downtown area of Portsmouth and looking for an excellent meal with top-notch service and a really nice atmosphere. It's easily walkable from the shops and theatre or either of the downtown hotels.
We both started with a wedge salad ($7) which was good, but unremarkable. For entrees, my wife went with the Pan Roasted Salmon with creamy parmesan polenta and shaved brussel sprouts ($24) while I chose the 12oz. Filet Mignon ($34) and a family-style side of Broccoli ($6.50). I also ordered the Gorgonzola cheese sauce ($1) from their variety of sauce options though for the life of me, I cannot understand why they would charge you a dollar for a sauce on a $34 a la carte steak. To me it seemed petty and beneath the rest of the experience.
That aside, the entrees were cooked to perfection. The filet was simply incredible; my wife enjoyed her salmon thoroughly and the the shaved brussel sprouts with the smoked bacon vinaigrette were a standout.
Our waiter, Jose, was excellent. He was attentive without being intrusive and paced the dining experience so it ran like clockwork. It sounds simple but anyone reading this knows that its no, so hats off to Jose; nicely done.
All in all, I would recommend this restaurant when in Portsmouth and I would definitely eat there again.