Let's see...
I wouldn't say that 4-MAR is as addictive as meth, but it definitely has addictive potential (from a psychological viewpoint) like all stimulants. One reason I would consider it 'less addictive' than other stims, is because most people find it inferior to them, thus they don't wnat to do it as much.
I also believe that to a certain extent, the very long duration for the 4-MAR high makes it a bit less likely to be abused -- simply cause you won't always need to be chasing the dragon. At leas that is how it is for me.
As for injecting it -- it was a bit of a disappointment...and it left a weird bruise on my fiance's vein (he does not typically bruise) even though the injection itself was painless. Anyway, 4-MAR didn't really seem to be that much better injected than my preferred method of doing it (orally). Maybe I didn't do enough...in any case, I would have gotten higher off eating that amount than I did from injecting it. It's really weird how that works....