Here are some that I can think of on the top of my head:
- It's volatility in price(currently). Hence holding your funds entirely on bitcoin is a huge risk despite the advantages.
- Very unsafe for careless and technologically-illiterate people. Logging in to a phishing link? Say goodbye to your exchange's funds. Forgot to list down your wallet's seed? Say goodbye to you wallet's funds.
- Unable to operate offline or non-electronically. This is a downside on more on the 3rd world countries, whereas most poor people can't even afford smartphones or any device that can hold bitcoin.
- Not-so-good transaction fees and time. Transaction fees and times are definitely alot better now compared to months ago, but I still remember the days when txs were almost instant, with very very low fees.
- My personal opinion: The name "bitcoin". I personally think it sounds like something a person involved in pyramid schemes and Ponzi scams would use.
Feeble capitalization of the market of bitcoin is the reason of the majority of shortcomings. When the market grows to the one tenth part of the market of traditional assets (an assets, shares etc.), many problems will disappear. Because it is a problem of absence of the accompanying market infrastructure. There is no sufficient capitalization - there is no potential motivation to develop this infrastructure. Those who will develop infrastructure, shall have an opportunity to earn on service of the market and its participants