Yes, have been there in Feb. Weather in Jamaica in Feb.is usually good (dry). Using monthly weather stats, Feb. is the month with the least amount of rainfall. But! Winter can be very breezy and the north side of the island seems to be worse than the west side. (Negril)
N Resort is very rustic and needs help. Don't expect a pleasure palace. If you don't expect much and want to be naked 24/7, it will suffice. Just lower your expectations before leaving and you won't be disapointed.
...and no pool is not heated and ocean temp is a little cool, but not cold. Remember it is winter. The wind will be your biggest obstacle to the sea in the winter. Bottom usually gets stirred up and surf is sometimes rough.
As stated earlier, wind is the biggest drawback. Mornings are quieter than later in the day. There's a reason for the fencing on the ocean side of the pool. Water temp was never cold, and even with the wind, the air temp is hot.