The Spell Sword, is, IMHO, extremely weak. It's not very exciting—dreary really. The Forbidden Tower is better. I find the mechanics of "matrix work" to be very ad hoc, with a lot of problems that are solved by deus ex machina hand-waving. Overall, it's less interesting than your average fantasy magic system, really. However, interesting parts of both works are the people and the relationships, which go through significant, interesting growth and change (moreso in The Forbidden Tower), and the relationships are complicated in interesting ways by the telepathy between the characters. I am have a telepathic premonition (okay, really, I've just been reading summaries)... that the dullness of the telepathy is going to plague me through the whole series, but the problem is, due to MZB's skill in building, revealing, and evolving characters, I'm hooked. :-/