How to measure software release success with limited information

this is kind of an open-ended question as I'm looking for some ideas on how to measure software success. I'm in a situation where a third party vendor is doing the development of the software, so I don't have access to the actual code. However, I do have access to the number of hours the developers spend to get a sense of the size and effort of a release, as well as the system which houses all of the business requirements, system requirements, bugs, change requests, test cases, and reported incidents. I would like to be able to compare the success of releases of different sizes based on the information I have. For example, if a release was 5,000 dev hours and 10 bugs resulted, vs if a release was 1,000 dev hours and 10 bugs resulted, the 2nd would be much worse. Then incorporate test case data to get an idea of how well the software was tested, etc. If anyone has any experience with this, or knows of any industry standards and can offer some advice, I would greatly appreciate it.