Cheap Wolfcraft 4525 Drill Guide Attachment for 1/4-Inch or 3/8-Inch Drills

I recently purchased the Wolfcraft 4525 Drill Guide for a woodworking project. I do not have room for a drill press and needed to make some holes for some bookcase shelves. So here is the good, bad, and ugly.
The Good:
1) It is a relatively well made tool. I have dropped it several times while it was still attached to my old B & D 1/2" drill with no damage. The spring action and adjustable angle are relatively smooth.
2) It helps make repetitive drilling much faster. It is much better than taping the drill bit to mark a desired depth
3) It makes pretty good 90 degree holes
4) There is nothing else quite like it on the market.
5)Stores easily
The Bad:
1)The play in the slide and bit attachment keeps the bit from always landing in the same spot. I think using brad point bits would make centering much more accurate. I also think a few modifications to the design could fix the problem.
2)The blue knobs on top that hold the desired angle seem to come loose often
3)Setting the right depth can be tricky because of the pressure of the springs. But once it is set it does not become unadjusted easily.
The ugly:
I think Wolfcraft should spend a little more time developing this tool. It is a cheap, simple, and effective replacement for a drill press. I would be willing to pay more money for a more well designed unit. Get more detail about Wolfcraft 4525 Drill Guide Attachment for 1/4-Inch or 3/8-Inch Drills.