Review my app: GroupDocs.com – Share, View, Sign, Compare and Convert Documents
groupdocs.com
groupdocs.com
I don't think the design really fits your service.
If you can answer the following question in the first screen of your landing page, you'll make it easier for potential customers to become actual customers: "How will this app make my life better?"
I'd be happy to help you answer that question for your customers: http://www.hnofficehours.com/profile/philipmorg/
Also - I'd probably add an about us page. Might just be me, but websites without an identity make me skeptical why the site was created. I see you guys have posted a blog post but adding something about yourselves can't hurt - especially when you're planning on dealing with people's sensitive info (again - going off the tax form example).
When did you launch this? There's a ton of functionality here - seems pretty well built out.
yet an e-mail address is required for logging in. Seems like it's more than "just in-case...".
Also, I think your sample documents are not good examples of what your app can do, and a couple of them (1st, 2nd) are kinda low resolution.