For a game that's free and available to play straight from the xbox website itself, you can't really complain. It's already a known game on another platform, so this is a great addition.
For those who don't know what it is, Wordament is a game where you have 2 minutes on the clock to find as many words as possible on a 16 piece board of letters. The words that you find all need to have the letters linking around the board so you can't go picking letters that are scattered around. It gets you thinking (hence the educational part), and you are in constant competition with a load of players all over the world that are playing on the same board! The higher you score, the higher rank you get on the leader board after each match. Obviously if you try to make words that don't exist the pieces will flash red and you'll get no points.
From my short time on the game so far, I've randomly found words that I didn't even think existed so in a way it does help you to learn your vocabulary while at the same time test what words you do know, whether big or small (although the bigger words do score higher!). There's also the occasional themes of words that the game asks you to look for as well which is a nice touch. Sometimes there are pieces with two letters on them so it makes you think a bit more with how that could be used to your advantage in the 2 minutes.
Another great factor about this game is that it comes with some nifty achievements! There are 10 altogether all worth 5 gamerscore making 50G for the game. They won't take you too long (apart from the play 100 rounds one) so just sit back and enjoy! Certain ones like finding the longest word on the board and getting in the top 50% of the leader board may be tricky but there are already really helpful solutions on TA to help with that.
All in all it's a fun little game which can give you anything from a few minutes to a whole afternoon of enjoyment. It's free, easily accessible, fun, and comes with achievements! Why wouldn't you play it?