I've been asked about creating databases using Access Web Forms (Web Apps) about a dozen times this month so far. Here's my current line of thinking about them:
I don't like Access Web Forms... YET. I think in 3 to 5 years they're going to be awesome, but they're still in their infancy and I can't get behind them. I'm going to be showing how to use them for REAL simple databases in an upcoming lesson, but they're just too simple to be of much use at this time. Microsoft needs to put more time into developing them for serious databases.
My recommendation at this time is to use a DESKTOP Access database and to publish your TABLES to a Sharepoint server. You can work with a team of people on Sharepoint and still have the FULL use of your Access code (VBA included) from your traditional databases. Web forms just aren't there yet. It's a little slower than using a Web form, but you get much more power and flexibility.
Of course, this method only works well for a team of people you trust. It's not a good solution for a public-facing database. If that's the case, I strongly recommend building your site in a REAL web language using server-side scripting, such as ASP. I show how to do this in my Web Database Seminar.