Great app, does the work it's said to do, and seems to help very well with teaching how to use comma's and how to write sentences correctly.

HOWEVER!
If you are a fast writer, then I CANNOT with good conscious recommend this app.
While I was making a long comment on Facebook, the process was made longer by having this app enabled while writing, because the app could not keep up with my speed of writing, and caused Firefox to run very slowly and laggy, making me wait a second or two before I would be able to see what I've just written, and words would more often than not be jumbled into each other as I had not paused a split second between each fully spelled word so that the app could keep up with controlling words and sentences.

As soon as I had disabled the app, everything went smoothly and perfectly again, and I could write at my own speed again with no laggs or anything.

If the creator can somehow fix this issue, then I would give the app top rating, but seeing as how I want to write at my own speed with no issues, I cannot give this a better score than a 3 star score.