Advantages of steemit:

• steemit is blockchain based
• users earn money for writing articles
• that money is actually a crypto currency
• steemit is open-source
• there is no annoying advertising
• the site is fast
• users are most of the time well educated and polite

Disadvantages:

• the amount of users is (still) comparable small
• no private messages to (an direct chat on the site with) friends are possible
• the editor to write messages is still rather uncomfortable (especially if you wrote something already and then notice you forgot to click at "editor" ...)
• images and videos have to be uploaded on external sites