I feel the need for a further explanation.
The cheapest way to make a guitar pedal power supply is to have one power supply, with a single mains transformer and a single DC regulator, converting from the incoming mains down to 9V DC (or whatever), and then make that power rail available at multiple sockets wired in parallel -- effectively daisy-chaining the one supply to every pedal.
The potential problem with that is that if there's a fault in a cable, or a pedal goes phut and shorts the supply, it could take out the whole power supply and stop everything working. And if any pedal dumps noise into the power rail, it gets shared with everything else... not cool!
So the next level up is where the main power supply converts from mains to some convenient intermediate voltage (via a single mains transformer again), and then that is further processed to provide the required individual 9V supplies (or whatever) via several independent regulating stages, one for each physical output.
This kind of PSU will usually claim to have 'independent outputs' -- but is basically just means that each output is electrically buffered, so a fault on one won't affect all the others, and hopefully noise from one wont get passed back through to the others....
However... all of the outputs share the same ground reference
so plugging all your pedals into it can potentially result in ground-loops between them, with all the corresponding hums and buzzes... (particularly when the pedal line up includes digital effects).
So this is the kind of device you're currently considering. It can work perfectly well, and clearly some here have found that. But you should be aware of its limitations and the potential for problems.
The most expensive -- but proper engineering -- solution for a pedal power supply is either to have lots of separate mains transformers, or (more usually) a single mains transformer but with lots of separate secondary (output) windings.
Each of these separate secondary windings (or separate mains transformers) is connected to its own separate regulating circuitry to generate completely separate, isolated, independent power outputs. In this way, none of the power outlets share a common ground, so there can be no ground-loops between pedals. Guaranteed to be completely noise free, regardless of what pedals you're using.
But those transformers (or multi-secondary transformers) are expensive (and heavy). This is why the best pedal PSUs cost £250 rather than £50, but also why they are so much better, in a technical sense.
You can see all the separate secondary winding connections feeding separate independent DC regulator stages clearly in this pic of the inside of the Oktopus: