What is a web apps end to end testing

After all the development is done and the features have been crossed off the functional document as “Complete”, how do you conduct an “end-to-end” test to make sure the application is sane and should be given to a client. Here is my list for any given web application.

1. No Flow error ( the application doesnt stop anywhere because of a bug)
2. Fonts/colors/ and text throughout the application is consistent ( there is no accidental bold or different font anywhere)
3. All the validation errors on the forms are graceful and shows the errors nicely.
4. There are no spelling mistakes any where on the application.
5. The form designs are nicely aligned and looks good to the eyes.