Ethereum is very interesting for a couple of different reasons: Vitalik is a genius, many companies are researching the blockchain, many ICOs will happen in the future based on Ethereum...
Biggest downside is that so much ETH is being raised during the ICOs that the price has risen artificially. These companies will want to have fiat money in the near future to cover their costs so they will sell some of their ETH, which will lower the price of ETH...
ICOs would, and in fact, increase the demand for ETH. Investors have to buy ETH first in order to participate in ICO. Even if the token issuers sell ETH after fund raised, it immediately absorbed by other incoming ICOs.