This is a decent product, until you look further. However, despite its relatively high quality, it suffers from a few problems.
There is no mention of how frequently the figurines that turn into the characters appear, nor how one would get one (other than a brief crafting blurb). They are apparently spontaneously created chess pieces that are enchanted. I know d20 doesn't really come with any settings attached like a certain parent game did, but how hard is it to write up some flavor to break the space between numbers up? They're basically hirelings but totally mechanical.
On the upside, it does have a good degree of unique content, and shows new spells, equipment, and feats on character pages for later explanation. The art, if cheesy (and the pawn does not look human, despite being stated to be, he's more of an elf in my opinion), is decent in quality, though it's not a selling point.
On the other hand, it's too dependent on other works by the author. I know it's part of a book, but then explain it. Using standard classes instead would be easy and not too damaging. The typesetting is of about average quality, and for a maker with 50+ products, they should've gotten that right by now. For some reason it made my eyes hurt a little, though that may not be its fault, since I've been traveling recently and a bit tired.
It's also short. 8 full pages of content, if you don't count the front cover [which has a little stuff, so it's a mite unfair], the advertisements for other products which it kinda sorta halfway requires, and the legalese, leave you wondering about the other stuff. Similar chess sets are mentioned, but not shown.
Good idea, good writing, bad presentation, bad prerequisites. It's still got useful stuff for any game, but it'd really shine in conjunction with the content it requires, or with it already modified (they say how to make alternatives, but why should a GM pay to make up his own content based off of someone else's?).
Also, just nitpicking, because I know that it's fairly common to do stuff like this, but some of the feats are unbalanced and arbitrary. Why need 52 hp for a feat? Why not a certain Constitution and level?
If you're too lazy to come up with your own stuff, or if you want a chess motif, go for it, otherwise it's just not worth it. Use a character generator (and there are many for 3.5) or make some yourself by hand if you have the time and effort.
Or, better yet, just play a game of chess. You get the chess motif, and you don't have to buy other stuff. And you don't have to do paperwork or interpret arbitrary numbers for it.
tl;dr: It's cheap, literally and figuratively. Buyer beware.
Reviewer's Note: I am snarky today, so if this is a little harsh, tough. I also like chess, even if I can't play it myself, so this has to compete a lot. No, I don't hate d20, I just prefer stuff that doesn't try to rip off other stuff that is perfectly enjoyable and add more stuff.