First off, the founders pioneered cryptocurrencies in Europe in 2009. Subsequently they created Paymium in 2011, making it the first European Bitcoin exchange.
Paymium is working hack-free since 2013 and they even have mobile apps for Android and IOS.
So, this ICO is coming from serious company with enough money and 5 years experience in the cryptocurrency field.
They can be believed in

Combining a Centralized Exchange with Decentralized Settlement

The main idea of BlockchainIO is follows:
cryptocurrency exchange, but secure (They are gonna use cold storages) and approved by European auditorial company

the main features of Blockchain.IO

1. ICO/tokens listings - there will be a fee charged for a listing, and if the ICO was successful, the token will be listed on the exchange automatically

However, other tokens will undergo drastic selection process and some projects will be turned down

1. Partners of Blockchain.IO

   1. Newfund - VC capital firm, raised 800 mil $ in 2008
   2. New StartUP VC firm, lead by Xavier NIel
   3. Paymium - euro/BTC pairs, years of experience

2. Actually good founders

   1. Pierre Noizat - CEO of Paymium, MBA from Columbia University in New York
   2. Dominique Rodrigues - 15 years of engineering experience, PhD in numerical simulation
   3. Pierre Michard - Pierre holds engineering degrees in both
      industrial computer science, electronical and telecommunication
   4. Anthony Grouselle - Anthony is a Web & mobile developer
      with 10 years of experience in the US, the
      UK and France. His skills include algorithm
      development in fields such as trading
   5. Samuel Bezerra - the guy won the Microsoft prize for the best mobile application in Paris
      Hachathon
   6. Laetitia Zito - CFO. CFO with more than 10 years of experience
      in finance management and control. She
      has worked in Canada, US, and France;
      and is an expert in international business
      management. Laetitia holds a Master
      in Financial Management & Controlling
      from ESSEC Business School.
   7. Paul Gaston Gouron - since 2015 he is in the field and even developed his own coin, Timecoins Rali, that enables time sharing. Works on machine learning in his spare time

3. Good roadmap - they'll be rolling out new features and liquidity services and custodial exchange in 2018.
   Lending will come in early 2019.
   [Photo of roadmap]

4. Short & Long Margin Trading - Long trades will automatically be closed by the exchange when amounts invested
   exceed borrowing capacity. At this stage, the borrowed funds are automatically
   returned to the lender along with accrued interest. Basically the ability to go short and long on the platform

5. Cryptos will be chosen by special team of experts -
   Cryptocurrencies will be listed on the trading platform following a strict vetting process
   (sustainability, technical, and deep protocol review) by our team of blockchain experts. Regular updates and publications will inform platform stakeholders and
   the community through altcoin technical reviews and financial analyses.

7)** Peer-to-peer Lending** - the thing I liked the most.
Traders who need to borrow funds to
trade on margin will be able to borrow from other platform users.
Lenders will earn interest on borrowed
funds.

Interest rates will be set based on
supply and demand using a centralized
order book and an order management
system.

link to their site: https://blockchain.io/