Project Manager's Portable Handbook, Second Edition

It is important to be able to anticipate whether a project will be either a success or failure. Success or failure is determined by the measures applied for evaluating the project during its life cycle and when it is complete. Looking ahead and determining those actions that contribute to success or failure can often avoid adverse outcomes.
The words "success" and "failure," like the word "beauty," are in the eyes of the beholder. In the project management context, the word "success" is used in the context of achieving something desirable, planned, or attempted that is, the delivery of the project results on time, within budget, and having an operational or strategic fit with the enterprise's mission, objectives, and goals.
The word "failure" describes the condition or fact of not achieving the expected end results. Project failure is a condition that exists when the project results have not been delivered as was expected. However, if the project results are acceptable to the user, then overrun of costs and schedule may be tolerated.
Determining success or failure requires that performance standards be developed on the project, which can be compared to the results that are being produced. It is important to remember that a key performance factor is whether or not the results of the project can be effectively used by the customer.
Product success or failure may be perceived differently...