It's an impressive application, full of the features that users of databases like Access are accustomed to. You can create complex relational databases made up of several tables of information, and then query the data using visual query builders. The tool also supports SQL queries.
If you've been using a spreadsheet (like Excel) as a database, as most of the world does, the learning curve for a real database like Zoho DB will be painful. Zoho DB lets you start out with a single spreadsheet-like table and add in database features from there, which is a help, but a tutorial and more help text would be welcome.
Zoho DB is a fully Web-based application, and it shows in the best ways. Every report or graph or table view that you create in Zoho DB gets its own static URL and embed code. Zoho DB can be used to create powerful applications that can then be embedded in Web sites for real-time data collection or display. It's the kind of thing you just cannot do with an offline app.
I did run into a few snags in trying out the application, though. While it lets you kickstart a database by importing spreadsheet data, you can't actually import an Excel file. You have to convert it to CSV format or cut-and-paste the data, which limits the richness of the data you can transfer. Also, Zoho has another great app, Zoho Creator, a Wufoo competitor for building rich data input forms. I couldn't find out how to get Creator data into DB, which was maddening. I would expect Zoho to integrate Creator and DB shortly.
Insert standard "Microsoft and Google are falling behind" paragraph here.
See also: DabbleDB.