I've had the pleasure to experience a Blind Guardian gig at Saarburg on April 26th, 2002. It was quite nice, but left me underwhelmed, especially considering the hefty price of 24 euros per ticket.
First, let me say that I own not a single Guardian album, but having lots of friends which are heavily into metal (hah! pun), especially the kind of melodic power metal of which Guardian represent the quintessence, I've heard their music for countless times. Especially their latest album, A Night at the Opera, but much of their earlier catalogue, too, is thick with overdubs. According to a friend who read about it in a guitar magazine, in some song the lead guitar was overdubbed four or five times!
Thus, they sound --in my opinion at least-- much better live, at least when it comes to the instrumental parts. Their music is better with some transparency. It's standard power metal fare, as has been said before, but well executed. Personally, I think all the pentatonics and ecclesiastical modi get boring after some time; but this is neither Purple nor Heep -- expect no blues scales. The biggest disappointment were the raspy vocals. Maybe I caught them on a bad day, anyway the singers had problems reaching up to the highest notes. I wonder why a band writes and records vocal parts that high if they can't execute them properly on stage?
Overall, it was a great concert and had my friends raving, but somehow, the Uriah Heep gig I heard before Christmas 2001 rates much better to my ears. Suum cuique, I suppose. You may now vote me down for my taste ;)