The fact is that quality can be measured in cold facts, as well as in terms of user satisfaction and business savvy. In practice this means that to build a successful product you need -- at a minimum -- to do the following:

Verify your business case and product idea with your target users: A healthy business case takes into account existing market requirements and opportunities and balances them with development costs.
Ensure technical accuracy and maturity: The final product must be polished, bug-free, and thoroughly tested to ensure that it runs like clockwork.
Design for emotional appeal: The user experience and visual look should be geared to impress and to enable smooth operation.