The purpose of any osteoporosis drug is to reduce your risk of fracture, not necessarily improve your T-score. The T-score is just one of many risk factors and a means of measuring.
When you say your hips did not improve, do you mean that your T-score did not increase, that your score decreased, or that it did not increase a significant amount determined by the precision study done (I'm assuming your testing center does precision studies) on the DXA machine?
If your score stayed the same, you are determined to be stable and that is good. If it increased or decreased within the margins set by the precision study, that is considered stable and is good.
If it decreased to be considered significant as determined by the machine's precision study, then that is a loss.
The same holds true for your spine.
The Prolia is a new drug. I think it came out in late 09 or 10. There's not been enough time for people to have been on it long term in order to address your request for feedback. Because bone is so slow to respond to change, testing is done every two years. Only now will people who began the drug when it came out be getting a followup bone density test to monitor its effectiveness.
As for side effects, you have to weigh your personal risks for fracture (prior fracture, genetics, estrogen or not, other meds taken, balance problems, T-score, etc) against the proven benefits of a drug. The benefits should always outweigh the risks.
I hope this gives you some information with which to start a conversation with your doctor.