FolderGlance can best compared to FinderPop in Mac OS Classic. OK, maybe that's not fair, since I haven't found anything that really compares to FinderPop.
So, maybe you should think of it as similar to Ittec (which *still* isn't compatible with Tiger) or OpenMenu. But, unlink those CM-based folder-browsers, this one doesn't allow you to add other items (like apps) to your contextual menu. That's really useful for opening any file in, say, XEmacs, TextWrangler, or GraphicConverter.
So, this is just a folder-browser, but that's still can be an incredibly useful thing. I find myself missing this feature whenever I'm on a computer without it (Fake! is the closest thing I've found for Windows: http://web.telia.com/~u32102551/index.html).
However, where FolderGlance really falls short (for me) is that appear to pre-load the folder-hierarchy for the item you click on. You can customize this in the include PrefPane, but let's say you control-click on your hard-drive. FolderGlance appears to dive through EVERY folder (to the depth specified) before showing you the CM. Other CMs seem to build this on the fly, so the Applications folder (for example) won't be examined when control-clicking on the hard-drive until you mouse over that item in the CM.
Given how slow this pre-loading is, I prefer the on-demand method. Additionally, if you restrict the depth to, say, "2", then you cannot dive down deeper than 2 levels. So, you've improved the speed but reduced the functionality.
I don't want to discourage the Developer (I'm a huge supporter of freeware/shareware efforts), but I did want to put this constructive criticism out there for them, and to let other users know what to expect from FolderGlance.
However, your mileage may vary, so please post any other reviews, too!