They are great ways to get into coins early on before they hit the exchanges. A lot of the time, the companies will give bonuses for being a early adopter. When deciding on which ICOs to get into, I like to look at the whitepaper, the team, ICO structure, the community support on Slack, Telegram, and Reddit. If you can get into a Pre-ICO that is even better but many require minimum investments. Some Pre-ICOs that I recently got into were Enjin (Ends in a few days), AirToken, Kyber, and OMG.