Here's a quick list of things I don't particularly like:
-The title font. The graphic is ok, I might have gone with a deeper blue instead of the more "aqua" gradient you have there, and I don't really like the rounded arch of the banner. But the main thing is the font. Aqua backgrounds are hard to use for banners because colors don't stand out against it very well without being offensive (i.e. neon pink would stand out, but would be horrible.)
-The black borders around everything are ugly.
-Login/Register seems out of place. I can't really put my finger on why; maybe because it clashes with the rounded banner. Consider moving it elsewhere...
-At first glance I don't really notice the navigation bar because the links are too close together, are the same font as the content text, and are black like the border. Make the nav bar taller and less crowded. It should look more like the nav links that pop up when you go to "Features."
-When you click a link in the nav bar, consider highlighting which page you're on. Kind of like tabs (so you know which tab you're on) but without actually making tab graphics. Does this make sense?
-"Policy" at the bottom is crowded into that little section, and it's ambiguous what "policy" is. Sales policy? Privacy policy? Make it easy to understand what that is. Also consider moving it to the main nav bar, because privacy policies are a big thing these days.
-If you are having a sale, you want to make the 19.99 price stand out a lot more. make a new graphic along the lines of the one you already have, except use reds instead of blues to emphasize the discount.
-"Welcome to the Niche Toolset" could use a new font (i think it's impact at the moment- definitely get rid of that) that makes the letters appear less "crowded" against one another.
-The font for the main content is a little old, consider using a sans-serif font.
-Make a contact form instead of forcing your users to open their email client. Trust me, it's a lot more convenient for customers.
One positive: The box with a summary of all the features is good. Keep that, but maybe make the "much much more..." a link to the full features page.