I personally think yamaha R15 scores better in looks and I also heard that CBRs torque is very low when compared to R15. Its gonna be really tough to select btw the two kings of indian roads, i.e yamaha and cbr 150. I think cbr has a better upright stance to that of a sporty stance of yamaha R15 and many people complain that they have wrist pain when riding yamaha.
So I think buyers should take a decision only after test driving both.