Mostly ICO project have failed, but if you looking deeper into who the developer, how the coin movement and what makes this interesting which can success or not.
ETH ICO project, looks great with the revenues from ICO is billion dollar worth. And now they grow step by step.
It is true that good project ICO goes good but when they hit exchanges they just get dumped by the bounty hunters and some ICO investors who are just investing to get some little profit and dump it and the coin price goes below the ICO price so it is better to wait for the coin to hit the exchange and if the coin gets dump then you will get below the ICO price and you dont have to wait for the ICO to end as you are in buying from exchange and when it is rising you get profit, so it is so simple that better wait for the coin to hit exchange better then buy in ICO.