I was looking at the channel guide a week ago and saw "Celtic Thunder" on the PBS schedule. I thought, "Whuh?! Those guys are still together. How nice. Wonder where they've been?"
Well, no, they're not still together, and as other reviewers have said, the PBS Celtic Thunder is totally unrelated. The latter group probably makes better use of the name, though, as they're big, loud, and flashy. This Celtic Thunder is much more restrained and, in my opinion, much more tasteful. They play straight-up, no B.S Irish music, and do it well.
I would not rank them in the same league as the great Irish bands that started up in the 70s, say, Planxty, or The Bothy Band, or De Danann. But it's a solid effort, and "The Best Years of Our Lives" is a gem, worth the price of the album by itself.