Wasn't there for a party, but stayed for a night last year.
We found the experience disappointing and expensive. Came away feeling that management had a deal to learn about running a house/hotel and that the place looked great but was lacking on some of the basics such as heating and functionality e.g. room was cold, couldn't get tv to work, couldn't find plugs for hairdryer (and when we did they were out of range for the mirror so Mrs M was not pleased).
As the evening came on the main house was quite cold and drafty and no-one had turned on the lights so it was basically getting dark and wasn't cozy as it could have been.
Reviews on Tripadvisor seem to get better as time goes on so perhaps our experience indicates that there were teething problems which have been addressed.
For a group party it could well be a great location as it would be nice and intimate for a gang of friends. Having said that, judging by my short stay, if I was going to spend my money on a night away, I wouldn't be heading back there. There are plenty of other places around the country offering a more polished experience, imho.