To be quite frank, I don't leave reviews on stories that I simply can't read.
It's not because I don't care about the future of the written word. On the contrary, I'm in love with words, and have been all my life. I relish the interplay of language, and I delight in nuance and shading. Nothing makes me happier than to be transported elsewhere by a well written story.
But...
But if you don't care enough to run a simple spellcheck, if you prefer the sloppiness of text-speak, if you haven't the barest notion of how to use punctuation, if grammar is an elderly female relative good only for birthday handouts, NOTHING I say in a review is going to make you change. I've no desire to waste my time tilting at windmills.
The best advice I can give to anyone who wants to improve as a writer is to read. You'll see some common themes in published books everywhere. They follow the basic rules of grammar. They use punctuation appropriately. They spell words correctly. They attribute dialogue in a way that lets me know who's speaking without having to read back three paragraphs. They don't broadcast a change of scene or change in point of view with a banner headline. They research, so you don't have a medieval monk checking his wristwatch. (Brownie points if you can name the play in which Shakespeare makes a similar error.)