I've flown into Mt. Snow in the summer. Its not a difficult IFR approach, except that you're dealing with a Center controller who's got other things to do than provide vectors. So expect a full approach, and study the chart carefully because they might erroneously give you an IAP to a different airport.

As for an IMC departure: not as difficult as Aspen, which is very high on my Most Difficult list. But be very familiar with the DP, because there are real mountains to stay clear of. More significantly, you'll be out of radio contact for the first few minutes, because Center's radios and radar don't reach down low.

Last time I was there in the summer, there was grass growing on the runway. I don't know if they do a very thorough job of plowing it in the winter. Also, I'm not familiar with what sorts of pre-heat or electrical outlets are available for a cold weather start.