Overall, Nyko's
Charge Block Solo does everything it advertises, but there are a couple of issues that need to be addressed.
As mentioned above, while hooking up a pair of Solo units is all fine and dandy, if you happen to have three or four controllers, you will want to read the paperwork in order to make sure everything charges up as it should. Not only do you need to have the charging station(s) plugged into a USB 3.0 port so you can have enough juice to actually charge up all those controllers, but there are some cases where you will want to make sure some controllers are more full than others before adding a third or fourth battery to the load. This is especially true if you are charging up a completely dead battery. While I don't find this to be too much of an issue, it is something that has to be considered. Then again, if you are looking for a solution to keep four controllers of different system types topped off, you might want to break up the charging stations into two pairs so you can have an Xbox One controller and a PS4 controller on either side of the couch. If you are talking about more than four controllers though, I would definitely pay attention to the small print.
So, let's say you really need to plug in all of those Charge Block units into one device and you have to use the console's USB port. Not only do you need to remember to set up the console's sleep mode so that the USB port remains powered even when you've stopped playing, but you have another issue to contend with - those nice bright LED indicator lights on the sides of the Charge Block Solo.
While they definitely serve a purpose, they can also cast a lot of light, and if you are chaining two, three or four of these devices together, most likely you will have an eyeful of white light glowing from somewhere around your TV. Not exactly good and given their somewhat frenetic blinking while actively charging, possibly even a bit distracting. Other Nyko Xbox One chargers, like the aforementioned Charge Base, have a much more subdued indicator, and it's a real shame that the same design philosophy wasn't carried over into the Charge Block line, because I feel like this was a decision made from a design standpoint and a problem that could have been avoided. I have no doubt that there are technical issues surrounding the potentially convoluted three or four block charging station and how much power you need versus which order the controllers need to be placed. While still an issue, I can see how those issues would be hard to get around. When it comes to an apparently purely design-centric decision though, like the overly-bright lights, it's hard to overlook.
The Charge Block Solo is a great idea that is generally well-executed. There are some considerations to be made when you want to go beyond two controllers, but those issues aren't enough to keep me from recommending this product. Granted, if you've already got solutions to charging your controllers, the Charge Block line isn't going to provide you with anything extra - unless you just really want a cleaner and more unified charging station, of course.