There are lot of ico which have already been completed. Is there some resurs to see the statistics of successful and those that are growing?
There is a site that is entirely dedicated to showing stats regarding ICOs including how much ROI has been generated since the ICO based on the ICO price of the coin. NXT and IOTA are both pretty big gainers in relation to ICO price right now.
Even though ICOs can be successful, it can't be ignored that there are definitely risks involved in investing in ICOs.
There have been plenty of ICO scams including a recent one called confido, which took investor money and ran. You always have to do your own research and due diligence before you invest in anything since people are really out there for your money these days.