"This is the type of arrant pedantry up with which I will not put."
—not Sir Winston Churchill
Dude or dudette, we are going to be all up in your face about grammar.
We want the stuff to be spelled correctly, though we don't really care whether you use American or British spelling.
We want the thesis to be clear and up-front. If you run a sentence on, we are going to be all, "What the frack was that about?"
You will still know us as your kind. We care about the same things as you do ... plus that grammar stuff.
We have a lot of entries. We are looking for good entries. We're not necessarily asking for you to bring your best writing skills (or what you've been cruelly misled to believe is your best writing), but we do ask for writing that expresses complete and coherent thoughts, has correct word usage, and lacks punctuation abuse. In other words, we're asking for the same quality of writing your English teacher expects from you. That said, we are still an informal wiki, so we give a lot of leeway.
If you at some point grow tired of getting fixed, you might want to look into Tips on Grammar.