Honestly, I see it as a weaker ephedrine, which we know is relatively safe and quite efficacious. Hell, even amphetamines aren't that deleterious, or as bad as oft pontificated, especially in meager doses. The structures are similar and obv full blown amphets are the most robust of these, with all being sympathomimetics. There's very little truly empirical evidence on DMAA, however, its ubiquitous use in pwo supps for quite awhile there, concomitant with other stims (mostly caffeine), and how well tolerated and ostensibly (as in most cases) devoid of side effects it was, says a lot. Thus, seems okay as long as it's not overdone, as with all things. We do need more evidence, though... studies would be nice.
Here's a link to buy some if you're interested:
http://www.ceretropic.com/dmaa-solution/