The Coleman event shelter is a nice tent for a festival. I would'nt reccoment you to put it up when there is much wind because it is a real windcatcher. With heavy rain you can better support the roof. When there is some water on the roof of the tent there is a possibilty that the roof would colapse.
There was one destroyed at the side of us on Sunday in the high winds. They do look great though. Gazebos aren't really designed to put up with bad weather.
We bought one at the beginning of the summer and have used it every time we have been away with friends. It's brilliant. We use it to keep the sun of the kids and the rain off us all.
I can't quite work out how to put the pics in... so here are the links to the flickr albums...
The wind does worry me although it can withstand much more than I expected it to. We have found it a brilliant investment. Easy to put up... a few drips (but we had loads of rain!) and it is very useful.
I was camping in Dorset (Eweleaze) at the begining of August and there was one directly pitched in front of us to serve what seemed to be a large extended family. It looked great and served as a real hub for the family. Unfortunately we had a little bit of wind which completely destroyed it (probably beyond repair). I would be very nervous about buying or using one.
We had quite a bit of wind and managed ok. I think the event shelter works better without the sides on. We took the windbreak down on one day because it was resting on the shelter and putting strain on it. If you want to take it down overnight it is possible just to unhook the fabric and remove it whilst leaving the frame up. Fiddly but possible if leaving it up at night is a worry.
Nantcol Waterfalls is an absolutely gorgeous site - would thoroughly recommend it!