Yes, coconut flour tastes like coconut. It's very sweet tasting, so the taste would work well for a poptart, but there are other issues. When you are substituting a gluten free flour (coconut, rice, nut, bean, etc...) for wheat flour, you lose the qualities that the gluten brings to the baking. One very important one is the ability of the dough or batter to stretch so that the baked item can rise.
One way around this is to add xanthan gum to the recipe. Gum stretches! so you might want to add a little bit. A little goes a long way.
Let us know how your experiment turns out
How did I do that? I quoted myself and lost the original ...
Just beware of coconut flour.typically you use very little flour and A LOT of eggs. Don't try to sub it into a regular recipe as ms Liz stated above. If you want to try some gluten free recipes I recommend Elana Amsterdam's recipes.She blogs at elanaspantry.com.