You have a crush on the famous web portfolios or Coinbase Xapo? You say that it is finally easy to buy and use a crypto-currency? Do not rush too much on it because simplicity still a price.
THE PRICE OF TRUST
If there is one thing you need to know first is that you will have to trust a trusted third party. In other words, you will not have full control of your financial assets. It's like a bank, if the company decides to freeze your wallet, you can do almost anything. You should also trust the developers that manage your portfolio as we all know, a human can be corruptible.
CENTRALIZATION
It's like a bank account, you must pay attention to its portfolio transactions because there may be someone who has hacked your account. Indeed, transactions do not pass directly into the blockchain, they go first to a homemade program that the company has created. Safety then becomes almost the same as a simple private message on Facebook.
THE VULNERABILITIES
Web portfolios are stored on servers, which means that your Bitcoin can be vulnerable against malware. The best way to secure your assets is to put in what is called a "cold storage" (in general, it is written in the FAQ), or use authentication to two steps.