Well, I'm going to have to disagree with the "pretty basic" characterization. I'm not aware of any "free" sites that offer all of the features of CycliStats - they offer some of them (as do most ride loggers), but none offer all of them.

Some other advantages:

1) Native Windows program
CycliStats offers the ease-of-use of a native Windows program. Compare this to browser-based "programs" that are generally clunky and much slower to use (this is the same reason most folks don't do their word processing in a browser window). I guarantee you can slice and dice your ride data much more quickly and easily in CycliStats than in any browser-based log.

2) You don't have to be connected to the internet, or remember a password to log onto a site.

3) Your ride data is stored securely on your own computer.
There's no guarantee that a "free" site won't someday be abandonded by its author, causing your ride data to be lost.