I've been coming across the term Proof of Stake quite often as of late. ETH is going in that direction. What are the advantages and disadvantages of POS vs. POW?
There are a few different ways of looking at it.
Proof of Work gives people with mining hardware a fairer chance at collecting whatever coin they're mining whereas Proof of Stake provides additional coins for those that already hold them.
Advantages of PoS is that it effectively eliminates electricity usage because you're no longer having to power hardware to mine. Disadvantages is that you have to buy into whatever coin you're trying to accumulate if you're planning on accumulating more via PoS.
There's no perfect in between. PoW is going to have mining farms driving difficulty up and profitability down for the Average Joe and PoS is going to result in wealth accumulation more for the already wealthy than it will for the Average Joe, but at least they won't have to purchase hardware and pay higher electricity bills to be able to do so.