my short answer would be: bad at punctuality. Frequent delays bigger than 10min.
France for example is better at punctuality IMO. But granted: smaller population density, therefore less stops needed in rural areas. And lower population density made it also a lot easier to build many complete own tracks for fast trains (TGV). Also more centralized way of thinking, so if you are around Paris: good, if you live far away of big cities, not so lucky.
> smaller population density, therefore less stops needed in rural areas.
I see this argument regularly, but I do not find it very convincing. There are places in the US about the same size as France with much lower population densities as well. France is about the same size as Texas. Surely there are Texas-sized bits of land with similar densities as France in the US.
> Also more centralized way of thinking, so if you are around Paris: good, if you live far away of big cities, not so lucky.
The network is still very centralised, but it is much better than it used to be. Thanks to the Paris south and east bypasses, as well as progress on the high speed line in the south made things like Lyon-Lille, Lyon-Toulouse, Strasbourg-Nantes, or Marseille-Bordeaux quite nice. Lyon-Bordeaux is still a pain in the backside because of the mountains in the middle.
I haven't taken European trains, but Amtrak in the US is often atrociously late. They pay to rent tracks from freight companies and have to cede right-of-way to not block them.
France for example is better at punctuality IMO. But granted: smaller population density, therefore less stops needed in rural areas. And lower population density made it also a lot easier to build many complete own tracks for fast trains (TGV). Also more centralized way of thinking, so if you are around Paris: good, if you live far away of big cities, not so lucky.