I think it's got way too many letters in it.
What is your opinion about Kabbalah?
Has its roots in Jewish mysticism. Sounds like fun. It was just one of the pseudo-sciences during the period we were struggling to develop knowledge about what, how and why. It's about as useful as astrology.
Although it's long out of fashion there are still those who contrive to use it in ways that the ancients never foretold; go read Tyto's answer again. He is truly a master.
Seriously, though? It's as valid as any other formalised approach to understanding the spiritual -- which is to say, not very.
I've read about it, along with a number of mystery religions and I always end up at a point where I feel like my brain is going to melt out of my ear-holes, and I think "This either means something or it's a load of old twaddle " and then all I want is a cup of tea.
Most of the time I look to the people that are a part of this thing, Chris Martin from Coldplay (who has the flower of life all over his new album), the young chaps from One Direction (with their red bracelets acting as a amulet to ward off harm) and Madonna, and with regards to the latter, she may be extremely fit for her age but I wouldn't of wanted my Grandmother gyrating her crutch all over a stage and over young dancers. My Grandmother wouldn't of dreamt of doing that, not even with a few G and T's inside of her, she had too much class. I tend to judge religion by those who practice it.