I am a 27 year old (ex-)physics graduate student and I am quitting this graduate program to enter a new PhD. program in theoretical CS. As for mathematics background - I have always been interested in geometry and have done graduate level courses in Riemannian/algebraic geometry and I have research experience of using harmonic analysis.
In my few months of experience of studying theoretical CS I have become increasingly drawn towards subjects like graph theory, spectral graph theory, unique games, complexity and especially quantum complexity theory.
Is there anything I need to be cautious of while taking this plunge?
How good are the career prospects in this subject?