First of all, let me say I'm a fairly average VB programmer, probably a bit more advanced than this book is intended for, but I'm not that great a programmer, period. In fact, that's why I use visual basic. I started off with C (in fact, I own 2 of Mr. Walnum's books on game programming in C), but I wasn't very good at C, and even worse at C++.
Anyway, after my first glance through this book, I said to myself, "Wow, I just wasted $an amount.". (Actually, my first thought was I'd seen this before, in fact, a lot is identical to one of Mr. Walnum's game programming in C book from about 6-7 years ago).
But upon closer inspectation, that's not really fair. After reading the book, it is a pretty decent book. It is aimed the beginner, which is probably a good thing, since there very few game programming in VB books, and this is the only one for VB6.0, and the only one still in print. The games start out very simple and gradually get more complex, but even so, you're not dealing with very complex games.
For instance, 1/3 of the book is dedicated to building the game "Moonlord", which rather than being a 'Space Adventure game' (as the book describes it), is basically a 'Star Trek' clone, which was one of the earliest computer games ever. It was the first computer game I ever played, back on my TRS-80 (with tape drive) in the late 70s. It also later appeared on the Atari 2600 video game console as 'Stellar Track'.
On the one hand, the book is aimed at beginners, so I can see keeping the games pretty simple. But that's just a bit too simple, I think. I mean, on Day 8 (of the 21 days), you're writing a blackjack games. Blackjack! Probably the 2nd simplest card game (the 1st being high card wins).
Besides being a bit too simple in places, the book is a bit flawed. First of all, the author used graphics (and programs converted from C++) from a far older book of his, which featured 16 color graphics (Not 16 bit, 16 colors total.) Because of this, a lot of the games you make look dated and sort of faded (Crystals, DragonLord, and the card games use graphics from the older book). But the rest just seem to use graphics inspired by it - not very colorful and very drab. This also is why the games seem very simple - those 3 were originally dos games, and some of the difficult bits in writing them were parts that windows does automatically (like the mouse, or a pop-up window, for instance). Converted to Windows, the games are far simpler.
Secondly, the author seems to have started out with the premise that Visual Basic cannot do graphics very well. In fact, early on in the book the author writes "If you want to write the next Quake or Might & Magic, forget Visual Basic.". While I would agree about Quake, the first 6 Might and Magic games are definitely possible with Visual Basic. In fact, until Might and Magic 6 (not the 6th game in the series, that was Swords of Xeen)the games all had a pseudo 3D view created by using sprites. Which is not only possible in VB, but is pretty easy in VB (easy because I managed to do it on my own).
Yes, it's slower than C, but computers are very fast these days. While the cd-rom states that the minimum requirement for this book is a 486 PC, you can literally buy a better PC than that for the price of this book. (I bought a 450 megahertz computer for an amount 18 months ago, and a Pentium 166 about a year ago for an amount with a monitor). And Visual Basic 6.0 seems to be a lot faster than previous versions of VB, and it compiles to a true exe, not just pseudo-code (like it used to).
So, you can have a decent amount of sprites and animation in VB games, but the author doesn't think so, and doesn't even try to tell you how to write a game with more than 1 or 2 things moving around, or any sort of moving background or real animation. All you get is very very basic information on sprites and almost no animation at all. It's not that difficult, either, so it shouldn't be out of scope for a beginners book.
Still, ultimately though, the book does live up to it's premise. It will teach you how to write games in Visual Basic in 21 Days. Just very simple games. And it does a very good job of explaining how the programs work, rather than just listing the source and letting the reader figure it out (which the older book, Black Art of VB Game Programming did), and the games are relatively entertaining, if simplistic.