Other than the Makershed "Ultimate Microcontroller Pack", I think it is a fine way to start. Why do I not like the Makershed offering? Price.
Look at the list of what it has; they spell it all out for you. Then go over to these two places (and/or Ebay - if you don't mind waiting a while for Chinese shipping):http://www.allelectronics.com/http://www.goldmine-elec.com/
I can almost guarantee you can get -everything- on that list and more from the above two places (with the only possible exception being the force-sensitive resistors); even with shipping, you won't be looking at anywhere near $120.00 for the parts.
Also - if you want a great bit of "fun" and a lot of weird parts to boot - pick up one or two of these (be prepared for hours of sorting, though!):http://www.goldmine-elec-products.com/prodinfo.asp?number=G9321
One of those boxes is easily worth $8.00; I once picked up a couple, and found some nice slide-potentiometers in mine that easily would've ran me $2.00 a piece or more elsewhere (it's all random, though - no two boxes the same; you tend to get a ton of diodes and resistors, though - lots of small components).
Also - that motor shield is kinda overpriced; it uses the L293 (or equivalent), which you can pick up cheap elsewhere. If you'd rather have a shield, though, on Ebay you should be able to find such a thing for much less than $20.00. However, maybe for your first time out, the controller and the shield should be bought "new" - but that "parts fest" kit should definitely be sourced elsewhere.