You done good, my MLPchan buddy. You done good.

You need to work on your spacing, the text seems to drag on and on and it's a bit annoying to read this all at once.

Super awesome story :D

That was super hot, though you might want to break up some of those paragraphs into smaller pieces. You should put more of your work here, it's good stuff.

a constant need to pee? think you need to get that looked out , could be terminal......

4534850 Mares in heat pee a lot.

4535384 oh ok.....

It smells like furries in here...

This was mostly very well written, with the right amount of detail, a reasonable storyline (good for porn), and good grammar (though there were a few typos - maybe get a final proofread just to sort these out). The way you wrote it wasn't generally boring and repetitive, as many other stories are, but there were a few words that were overused (e.g. delicacies).

There are a lot of aspects of the description of scat and watersports that I didn't like, but that's my personal preference rather than that you wrote them badly.