OTL amplifiers


Can anyone explain to me, in layman's terms, the advantages or disadvantages of OTL amplifiers? I have heard a lot about them, but have not listened to any to date. I am really a tube fan and want to reach tube nirvana and don't know if OTL is the way to go. Are they suitable for all types of music? Any information would be greatly appreciated. Thanks.
dfrigovt
A few people here have mentioned the Berning ZOTL amps. They are now produced by a company called Linear Tube Audio. LTA is able to build these amps at a higher volume than David could by himself and the price is lower. My ZOTL40 with EL34's sounds spectacular, highly recommended.

While the ZOTL amps are a brilliant design, they are very much not an OTL, as they employ an output transformer (see Dave Berning's patent).
My Aitos 801's are 32 years old and still running strong. And hot ;-).
They are handbuild and I have them in service with the man who did build them 32 years ago.
He still makes and sells them ( http://nl.aitosaudio.com/ ).