I have only been to Amsterdam and the airport in the Netherlands, it was a while ago, but no way did Amsterdam have a better infrastructure for bicycles 10 years ago than Barcelona has today.
I could be wrong, but the main streets didn't have the nice two way lanes like in Barcelona and the red light, coffee shop district is similar to cuidad vella and Raval, both in spirit and infrastructure, both are not optimal for anything.
I heard Denmark is on a high level too and maybe the Netherlands as a whole are much better. It has to be said that Barcelona is an exemption, Madrid and other cities don't even come close, apart from some few very rich pueblos on the coast.
At least in Barcelona you can use the main roads to get tangentially near your desired destination and from there it's a bit less luxurious.
I agree that left turning cars are very dangerous for more vulnerable vehicles. For example , to turn left , you have to get to the proper lane in time(not so easy, many people report map applications to have notorious delays in parts on the city), then check for ongoing traffic, sometimes the innermost are bicycles, then cars, then another lane plus pedestrians with no regards to red light green light rules.
It's also true that the lanes are often interrupted by other rather large streets etc.
But overall, it's a breeze going from one of the big parks to Barceloneta.
Big negative point is in summer, it's no fun, the heat can be horrible, and if you are on a red light next to a bus, the fumes and other car emissions are in your face and the temperature feels like it jumped 10 deg Celsius within 3 seconds.
To clarify, I am sure there are better small cities in that regard, I only tried to say Barcelona has the best solutions compared to other large cities.
The negative point of course is, it's downright hostile to car drivers, some people enjoy driving a car(I don't ever own a car unless I live in a remote area).