That's really about it.
Its more of a personal challenge than anything. You tend to want to push yourself just a little bit more in hopes of getting a slightly higher rank. One of the perks is that it also introduces you to some new words that your fingers aren't used to typing. If the game's vocabulary were enlarged a bit, it could be used for some decent typing practice.
One of the downsides to the way this game is designed is that you can't see which word you're going to be typing next, meaning that you'll never be able to maintain a steady flow of words as you type. You end up having to analyze a word, type it, analyze the next word, type it, then rinse and repeat which really puts a dent in the performance of people who are used to typing in sentences. A way to see which word(s) are coming up next would do a lot to improve things.

Yes, the game really does look this boring in real-life.
The addition of this game brings us up to a grand total of two typing games (that I'm aware of), the other being Super Stick Skirmish of Superb Scrappers. Kunark used to have some kind of typing game about blood and guts, but it doesn't seem to exist anymore. Maybe that's a good thing (blech).
This reminds me that I've always wanted to create some sort of typing adventure game. Maybe some day I'll actually get around to doing that.