I would say there are some better ones out there for the money as folks have said. Depends on how much wrenching you plan to do. I do a good bit of my own and like the Sears Professional Yellow Jack, although I agree with Hoople the Dyna blocks are a pain, if I could do it again, I would go with one that does not need them.
Was working on my bike the other day and noticed while moving the jack around the garage the block started to roll...thankfully I noticed before pushing too hard, else there could have been a problem.