It's way more interesting to look at the nuance and downsides of how Bitcoin works than to merely marvel, awe-struck at the concept of a distributed ledger.
It's been a few years since I was reading in-depth about Bitcoin, and I don't have references, but off the top of my head:
* It's bad for the environment, "wasting" so much electricity on more and more literal busywork... or is it? Apparently it depends where your electricity is coming from (it had better be cheap if you want to make money mining!) and whether you are actually causing additional electricity to be generated or just consuming surplus, or so I've heard.
* Control and power over Bitcoin is not all that distributed in practice. Mining a block would take prohibitively long for an individual, so there are mining pools where participants share in the spoils. Mining pools and exchanges have a lot of power. Just as the infrastructure of the Internet is run by big telecommunications companies whose routers talk to each other, there are various major players that make Bitcoin run, and there are occasionally decisions affecting the future and fate of Bitcoin, and Bitcoin politics, like disputes over protocols.
* In theory, Bitcoin is hard to fraudulently "take over" because you'd have to have more computing power than the rest of the miners combined, but if you control mining pools, or are China or something, I believe you could do it (and no one would necessarily know?).
* The rise of Bitcoin as a currency (not just a ledger/clock) whose value seems to just go up and up raises a lot of questions (IMO) about whether this is a good property of a distributed ledger system.