The core, fundamental advantages are:

1. Sock puppet voting has no value on steemit, but is a huge factor on reddit
2. Censorship resistance, which mostly applies to the underlying block chain and not the web site (so it won't have much practical end-user value until there are different ways to access the blockchain)
3. Ownership and participation-based pay for community members. Reddit recognized the value of this, and even tried to implement it, but found too many legal problems with simply issuing a cryptocurrency and abandoned the idea.

The rest will depend on how the community develops.