What's the straight dope on K2 'incense"

There have been a bunch of articles recently on K2, which is sold completely legally as incense but is ‘fake pot.’

http://www.independent.co.uk/life-style/health-and-families/health-news/kids-are-getting-high-on-k2-not-the-mountain-1917219.html

What does the Straight Dope have to say about K2? Are the side effects of it different that marijuana? Should it be treated by the law the same as marijuana?

Just a few days ago I bought three grams of the stuff from my local headshop and smoked a couple of small tokes. Got nothin. However, I’ll try again after I’m off the pager rotation and can afford to get high.

Here is another thread on a similar product, “Spice.” It may be of interest.