This is the perfect example of what I humbly believe every mathematics textbook should aspire to be like. Written in a highly motivational style, and with problems that are difficult but just hard enough to make sure you really "got" the material, it is by far one of the most enjoyable and rewarding books I've ever worked through.

There are very few, if any, instances common in other texts where a problem is set without giving the reader enough previous grounding, making it an ideal self-study book (which is what I used it for). If you can't do a problem, then you can be sure you didn't absorb the previous material well enough.

And if you don't know just how cool geometric algebra is when you start, you're in for a series of startling surprises!