I'm considering studying this as part of my AS levels next year. I previously had a chat with the tutor and he said out of all of the other subjects available, his students often told him that Philosophy demanded the most time but that they found it one of the most involving. I think I'll probably have another chat with the tutor when I apply around April. As far as I am aware it's always been a respected academic discipline since antiquity.
To my knowledge, philosophy is a respected A level. If you look at some of the examiners reports you will see how rigorous and analytical you need to be in order to achieve the top grades!