My PhD is in mechanical engineering with a minor in computer science. I would just remind you that a PhD is a research degree. If you really don't like research, it may not be for you. You should also be quite good at math since PhD-level work in CS is very math-oriented. The comments about the financial costs are also something to keep in mind. You shouldn't expect a PhD to be a net positive financially over your working life. What it can do is give you the ability to tackle a wider array of projects during your career along with the confidence to know you're capable of working in new fields. I've worked in spacecraft engineering, as a research professor in medicine, as a self-employed software developer, and am now working on a robotics project of my own design. Tackling new fields is not a problem because I know I can do the research necessary to get up to speed. Maybe I'd have the same attitude with only a MS, but I doubt it.