Interestingly enough most ico are said to be successful when they collect the full hard cap - which less and less ICOs do nowadays. I as an investor would say its successful when the price goes up afterwards and stays positive. But most of the time after an initial peak the price drops significantly until - if at all - the project makes some major steps forward.
So I personally like the fact that the hype around ICOs is a bit low right now which might produce more realistic pricing of new projects.