Whether you are reinforcing basic principles from school or homeschooling, these are a worthwhile investment both for understanding base ten and volume. However they are not the be all and end all; I though it was definitely worth buying the large box so that you get enough 100's and 1000's to be interesting, but note that it comes in 1-10-100-1000 pieces, so for basic maths it does not cover everything. You can however get a nice set of Cuisenaire rods from Amazon that complements the base 10 set very well, as well as fraction and decimal cubes. It is also worth looking at the Montessori web sites for other ideas.
As for this set, it looks a bit cheap and cheerful, but is entirely adequate.