This program is obviously a take-off on Mike O'Conner's freeware Layout, not that that's a problem. The latest version I have of Layout is 1.9, and it suffers from not working on a Finder that is active under MultiFinder. Customizer doesn't suffer from that limitation, but is otherwise similar. Another program, Layout+, is included in the Norton Utilities and does most, but not all, that Customizer does. To give credit where credit is due, both Customizer and Layout+ freely admit their origins and credit Mike O'Conner.
Customizer is for picky Macintosh users who love to mess with everything in their Macintosh environments. You know, the sort of ResEdit hackers who modify all the system alerts to include the word "Sir" at the beginning. Customizer isn't nearly so overt, but does let you change a number of the basic items in the Finder. You can change the icon spacing, which is often handy to do, the column sizes in the text views, the Finder's default font, and the colors in the Color menu, should you be working on a color monitor. Additional treats include suppressing trash warnings ("Yes, I'm sure I want throw out that program, you stupid computer!"), automatically aligning icons, opening the parent window by double-clicking in the title bar of a window, and using a literal disk icon that looks like a Mac with an arrow pointing to the appropriate disk drive. For even pickier users, Customizer can change the amount of time the Mac waits before switching to the watch cursor and increase or decrease the number of windows that can be open at once.
I won't say that Customizer is necessary, but the changes it makes can be welcome in certain instances. I find it's nice to switch my Finder font to a serif font every now and then because I find that serif fonts are a little easier to read. I also won't say that Customizer is a lot better than Layout, because it's not, other than being MultiFinder-friendly. You won't buy the Now Utilities for Customizer, but if you do purchase the package, Customizer is a pleasant addition.