I read through the whitepaper yesterday and am really impressed with the design and execution of STEEM. Subjective proof-of-work is a genius way of distributing coin. They've got the supply side covered.
Many altcoins have a unique demand-side proposition. For example Siacoin let's you buy distributed cloud storage. Maidsafe has the promise of purchased distributed webhosting. Litecoin gives you quicker confirmation times. DASH has increased anonymity.
Maybe this question is answered in the whitepaper and I missed it, but what is driving the demand side of STEEM? Where do I spend STEEM? What can I buy or do with STEEM that I can't buy with any other crypto?