I went to a wedding there in 2011. Really enjoyed the venue- it was beautiful- especially the grounds with maze etc for us to explore. The only thing I would say as a guest is that it's a bit out of the way and taxis etc were a bit of a faff. Too expensive to stay there as I recall so we were in Brockenhurst.
I second the guests staying. We looked at it, knowing we would need about 30 rooms as most of the family lived 4 hours away. Even with those numbers they insisted on minimum of 2 nights stay at 250 per night. Are you having the ceremony there? My only other negative is that the room that holds the ceremony and meal has an openning at the back onto the main corridor from reception, and the stairs going up, with nothing to stop non guests looking in. That said great for photos, love the little oriental room for family breakfast the next day.