We have finished what we think are the basic functionality of the app and the UI we agree is not professional (due to only people with back-end experience working on the project) but satisfies the functionality.<p>We are just going more public and into closed beta testing. I already heard from some users that UI for them looks ugly and had negative experience with it even though they were told it is only first stage testing.<p>My question is as UI work is very time consuming for us how far should a web app UI look to stay it is good enough for closed beta testing?
I'd try throwing twitter bootstrap onto your project. IMO, it's the easiest way to get something that "looks like a modern webpage" when you aren't far enough along to have specific opinions about things.