Does the bitcoin design make bitcoins suitable as a medium of exchange, a store of value, or both?
Today, it primarily serves as a store of value. It is inherently more useful as a medium of exchange, its intended purpose. Perhaps a bit ironically, its expected future usefulness as a medium of exchange is what is driving its present usefulness as a store of value. The thinking is that if you get them now when they're cheap, in the future when they're used as a medium of exchange (and thus there's much more demand) they'll be worth more.