Just want to say: I did a Ph.D in computer science 10 yrs ago and it was brilliant and has been fantastic for my career.

It was very hard at the time, in particular I remember a very bad moment when I was writing up when I suddenly realised that one set of results was totally invalid because of a flaw in my maths, implemented faithfully in perfect but wrong c++. This was the week before I went to start a new job in industry and it basically added six months to my degree while I redid everything and rewrote to account for the actual results rather than the rubbish I had generated before.

This is what happens in Ph.D's there is no sunny, easy path, but at the end it is worth it.