It likely would not be fair to suggest that bitcoin is without disadvantages since there can be some challenges in regards to both knowing how to use bitcoin effectively, protecting oneself and the responsibilities of being ones own bank, for those who choose to hold bitcoin and perhaps also trying to figure out successorship issues, which could be problematic if they keys (or how to access them) are not sufficiently explained and/or left to your chosen successors.
I would not call this a disadvantage of Bitcoin. Is it a disadvantage that credit cards and bank accounts can be hacked because people fall to phishing scams? If we are talking about the thing itself, disadvantages would be other things like it is hard to use or slow confirmation speeds. I would more call it a consequence of radically new technology, because they all have these problems. Teaching people how to use smart phones was hard when they were new, and it opened up people to many different ways to get hacked or lose money that didn't exist before.