It's interesting to look at wealth distribution of Bitcoin:
http://imgur.com/Vt7PvbW (source: http://bitinfocharts.com/top-100-richest-bitcoin-addresses.h...).
4% of users own 95.09% of currently available Bitcoins. I think that as the number of users increases so will value of Bitcoin in USD, wealth distribution will only get worse while making top even richer.
Even if wealth distribution doesn’t bother you, consider that part of these users(4%) mined/gathered it in questionable ways(mining via compromised systems). Early adopters gaining large part of Bitcoin for little effort seems silly too. I personally consider this unacceptable.
That might be the most important reason to dislike bitcoin right now. It is obvious why people who have a public ledger that claims they have a bunch of money would be fanatical about wanting other people to recognize that claimed wealth but not at all obvious what is in it for others.
However, even if that is fixed (e.g. some other similar cryptocurrency without that issue) I would add two more issues: 1) The system as a whole, for any possible system similar to bitcoin, seems vulnerable to being disrupted by anyone with enough money (at best this would still cost a fair amount of money, but I'm fairly sure it would cost a lot less and be less recoverable than trying to similarly disrupt (at least most) other currencies). 2) The estimates I've seen suggest that a huge amount of power is going into cryptocurrencies for no good reason. This seems like both a horrible response to global warming and (per point 1) is making the same cryptographic mistake that hashcash made on a much smaller scale. Hashcash seemed like a good idea at the time, but I'm not sure why it seems like a good idea to anyone now.
I would love to see more work done on various ways to implement robust local currencies rather than all this effort on trying to create fragile global currencies that suck huge amounts of power. Last I looked there were a few things available but it seems like a lot more can be done.
Both Dollar and Bitcoin are un-evenly distributed, but with Bitcoin the creation of new currency is fair, unlike the creation of new dollars by the people who have fractional reserve banking license.
those stats are skewed because a huge part of the bottom are people who have zero or very little bitcoin at all. If you only consider the "people who have at least 1 bitcoin" as a serious user, it's not that bad. Moreover, look at the barrier of entry to the top 20%: $600. So for one month's salary (at the low end of salaries) you can be in the top 20% of this economy.
