Yes it's definitely a good time to visit. You might be able to witness snowfall if you will go their in first week. But yes keep good winter wears with you because it's gonna be very cold there.
Yes !! it's absolutely the right time, if you're lucky you'll be able to see clear view of Himalayas from the summits in those regions! infact I'd suggest you to travel into the deeper woods of Nainital to witness breathtaking scenery and rich wildlife. :")