OVERALL - Another great source for all kinds of materials with a proven track record. Not just youth ministry resources also Children's Ministry, Women's Ministry, Small Group, Pastor and Church Leadership. One of the most respected names in the industry.
WHAT'S IT ABOUT? I'll try and hit several of the top resource locations in these reviews. Like most folks in Youth Ministry I first came across Group through their magazine. It's still one of the best out there. Now Group offers a much wider scope of materials. Add in things like Group Work Camps which can be a great resource for churches looking to do some mission work. I'm amazed at the massive amount of resources you'll find here. They also offer a national youth ministry event called the "Simply Youth Ministry Conference" that they do in partnership with Doug Fields. If you're looking for more choices and ideas Group will keep you busy for some time to come.
RESERVATIONS Same as YS, their mindset really comes from a non-liturgical, contemporary music kind of background and for me as an Episcopal youth minister I sometimes feel a vacuum for things aimed at my particular worship style. Fortunately there are other resources (that I've reviewed recently) that amply fill those holes. Occasionally I come across a resource whose theology just doesn't match mine but that's hardly surprising.
RECOMMENDATION It never hurts to have more than one source for your resources. Group should definitely be on your list when you start searching.