This thing is ridiculously tiny. The screen is supposedly the same size as the Wii U gamepad, but the whole console is way thinner than the gamepad. The dock thing is the same width as the screen and a 6.2 screen is 5.4 inches wide by 3.0 inches tall.
I'm just guesstimating here but add another inch or so for the bezel, and the dock is like 6.5 inches wide, probably ~2 inches deep, and roughly 6 inches tall. By comparison, the previous smallest console, the Wii, was 1.73 inches wide, 8.48 inches deep and 6.18 inches tall.
Current speculation puts the graphics chip on about the same power level as the Xbox One, maybe better, but most likely will be well below the PS4. I'm going to assume there is nothing in the dock that actually increases the graphic power, which is disappointing, as plug in graphics cards are becoming fairly common. I'm going to assume the dock is only for charging and HDMI output.
I wonder if it going to come with a separate charging cable for travel. Would be a pain if they expect you to take the dock with you.
Tegra's generally tend to run hot, and you can see that there is a vent on the top of the console for hot air to escape which probably means there is likely has a fan too. Based on past Tegra tablets, I'm going to say battery life is probably similar to the Wii U gamepad at 3-5 hours. The Nvidia Shield K1 8" tablet gets about 5 hours battery life.
Backward compatibility is also gone. Maybe can do the VC up to the Wii games, but no way the ARM CPU can run WIi U's architecture and not nearly powerful enough to emulate it even if it did have a disc slot.
I want to see the software, the system menu. Nintendo has to get that right. I hope they expand on the Miiverse platform. But software wise, they need to get into the 21st century. Every console they get a little closer, but they really need to have a dedicated experienced team that can bring all the online functionality together. Please oh please, let there be achievements and an API I can use for the site.