The Gatekeeper

My product owner said "Is the application is good to go?"
I understand he wants a simple answer like "Yes it is" but the answer is not that simple. I am facing this question second time as an agile tester. QA people be very careful to answer these types of questions, the answer will reflect your professionalism very much.
I answer him "According the positive use and user cases, application works fine, it worth a trial to start system testing in production". I can say he was not satisfied with my answer but its true. Being honest and responsible is two must quality a QA professional should and must have.
And for the first build in production of the application what happen? It is not working properly and correctly. So there they put finger on me and then I face a real challenging part to point out defects and problems(I am excluding the real defects here ;) and make it work properly on the second build. And now system testing is going on.

The main reason for this post is to show other QA peoples the importance and responsibility he/she bare in a software development phase and be very tricky to answer questions ;) best of luck all.