They work great with stick powder, OK with ball powder and are piss poor with everything else. Go figure, stick powder is what challenges the high dollar fancy measures and the Lee eats it like nothing, yet the small grain fine flake powders that any powder measure out there should eat with no problems at all are the most challenging for the Lee.
Is it worth $30, yes, in some circumstances. In some circumstances it works better than a $120 measure. Is it the only powder measure to have? Absolutely not, there are too many holes in where it works well to have it as the only measure available.
I have one, have used it quite a bit, and since I bought a Redding I haven't used it one time. I will give it what I feel is due, and tell you that there are places where it works great, but it really isn't all that good at all. You can go up from Redding a couple steps too, priced accordingly of course