Well, I've set up a C64 Mini in the dorm room and updated it to 1.1.4, so let's talk about it.
As I'm sure you all have seen it, it looks like a little Commodore 64 (breadbin version). The keyboard on it is decorative only, but considering how small the thing is, it wouldn't be practical to use anyway.
The system's menu is reminiscent of the recent Nintendo mini consoles, with a carousel of games that can be accessed by scrolling left and right. What I like about this interface, however, is that there is there is a screenshot and a small description of the game. There's no instructions for the game (you can go here for individual game manuals) but you can at least get an idea of what the game is like right away. The C64 basic is a nice addition, to those who would like to use the system as an actual C64.
You may notice the three icons at the bottom of the screen - the TV, the speech bubble and the wrench. They're pretty self-explanatory. The screen allows you to choose between three aspect ratios (fullscreen, Euro 4:3 and US 4:3), along with another version of those three with scanlines. The speech bubble let's you switch the language of the unit (which is initially set when you first start the unit), while the wrench lets you set the language of an attached USB keyboard, review the licenses of the various software on the unit, and look at system information, which is also how you upgrade the system.
Speaking of upgrading, you can get the latest firmware here. After downloading the file, put it in the root of a USB thumb drive, then put the drive into one of the available USB ports. Go to the wrench, then to "system Information." You'll be informed that there's an update, and be asked whether to apply it. The update will apply quickly, and the system will reboot. From then, the system can easily load roms. At that point, an inserted USB drive will show up as an icon to the right of the wrench. Now, put some C64 roms on your drive (formatted FAT32), and put it back in the system. You'll now be able to get into the file directory. Navigate the directory and pick a D64 title (not sure, but I think it'll also work with tape files, I really should try). From there, the game starts, and you're playing.
Which leads to the only real criticism that I have of the system. The joystick.
It's actual trash. Modeled on the Competition Pro, it's easy to tell that some corners have been cut. There are no microswitches on the joystick, and while the buttons work fine enough, the stick itself isn't as responsive as I'd like, especially with regard to diagonals. Often, I'd point the joystick in one direction, but go in another, which makes Boulderdash a bitch to play especially.
Thankfully, you can use USB joysticks, but recognition is spotty. Trying a PS4 mini controller and an arcade stick with the Brook Universal Fighting Board yielded no results. However, I was able to play with my Hyperkin USB GN6 controller. The D-pad works as expected, but the buttons are splayed out at random. In the menu, A button cancels and Y button confirms, while the rest of the buttons act as the utility buttons on that are present on the C64 mini joystick. Thankfully, both the A and Y buttons act as fire in game, so playing the games are still easy enough, but it takes a minute to get used to it.
Back to the positives, you can use a USB keyboard to interact with games (and BASIC), so you don't have to deal with the shitty virtual keyboard. The differences between modern USB keyboards and the C64 keyboard are highlighted here, and it's easy to use in games that require keyboard interaction, like Pitfall (F1 to start), Commando (spacebar to throw grenades) or the various text adventures that the system supports.
Lastly, the system IS compatible with non-powered USB hubs, so you CAN have the joystick, thumbdrive and keyboard hooked up at the same time, even though the system only has two USB ports. VERY handy.
Final verdict? While the joystick is less than desirable and alternatives will need to be looked into ahead of time, what we have here is a perfectly serviceable substitute for a Commodore 64 for gaming. Hopefully, future updates will allow users to use more USB joysticks and customize controls, but aside from that, it's a fine system. Can't wait for the full-size version of the console.