Really look forward for the day where I can buy stocks there. In my perspective the user experience is so much better. You own your "tkns". You don't need a broker or whatever to get access to an exchange. It works 24/7. Especially would be useful for people without bank access. By the way trading volume is already huge there.
person -> brokage -> market makers (hft) -> exchange
So my point is, I think in terms of fees it may be more expensive, since you can't interact directly with the exchange. Also try to transfer your assets from one broker to an other. Not always trivial.
Nothing similar exists on Uniswap, it's cool for people who know what they're doing, it's terrible for everyone else.
The guard-rails can be built in the new medium, and the result may actually be better than what we had before.
Also you have the risk that they might get hacked (although coinbase seems to be very secure).