In my opinion the biggets disadvantage is the more and more growing blockchain, in comparision with cc's of the third generation, the increasing lenght leads to the familiar problems : High transaction fees and long confirmation times going hand in hand with unconfirmed transactions due to too low fees set.
I think part of the problem with peoples opinions here is applying logic of other markets to one that almost no one understands.
I heard it put well by someone the other day that it is extremely rare if not unheard of that a new technology is made so publicly available for investment.
If you take the average tech start up for comparison the chance to invest is normally reserved for the likes of business angels and venture capitalist not Joe public.
All of a sudden you get a bunch of people, including me thinking that things look good or bad with no real experience in how things like this really work in the long term or where we truely we in terms of the cycle