Member Rara Avis
I'm guessing you mean the spellchecker.net module, Michael, which has been available for the UBB for about a year? I just spent about 15 minutes looking for a thread floating around here somewhere where it was previously discussed - because a few people vouched for my own findings when I tried it in my test site.
Slow and unstable. When their server gets bogged down, it has a bad tendency to "eat" your post. Worst of all, because it has to engage Athena in conversation to do its magic, it has the ability to crash our server, too.