Wii U is here, and we're not only playing some of the biggest launch games, but digging through its options, manuals and more. We're learning a variety of smaller facts about the Wii U, many of which you'll want to know when you finally have the system in your hands.

The Day One Update

The GamePad's Battery Life

Internal is Internal

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Here's what we've learned:We ran this story yesterday, but Wii U will need a Day One update to add Miiverse, Wii U Chat, the eShop and more. It's something we're having to do too - which is why you haven't seen a deluge of coverage on Wii U's operating system and interface. We don't know more than that - like how much space this update will take, or precisely when it will be available, but we know it's coming.You'll be using the touch-enabled GamePad controller with your Wii U a lot. But how long will it last? Nintendo estimates 3 to 5 hours for the device, though cautions that variation will depend on what functions you're using. Once your battery is dead, however, how much time will it take to recharge? Nintendo says it will take 2.5 hours to completely refill the Pad's battery.There has been a little confusion about where Wii U's internal storage lives. Let's clear that up for you. This storage is not housed in an SD card. In fact the system doesn't come with one at all. This is internal storage that cannot be removed or adjusted, so choose wisely when you pick up a system. If you want that 32GB, you need the Deluxe/Black Bundle.

The SD Card Situation

So Wii U's storage, as mentioned above, is interesting. There's the internal space that comes with the system, but then there's the ability to hook up a hard drive through USB (which we haven't tested yet) and the ability to insert SD cards. Here's a breakdown of what the system supports:

SD cards - up to 2 GB

SDHC cards - up to 32 GB

The system will not support SDXC or "UHS-type" cards. If you use a Micro or Mini SD card, you'll need an adapter. One thing to keep in mind, is that while Nintendo often provides guidance like this, it's entirely possible your larger SDHC cards might work. We'll see. This is just their official guidance.

The Life of a Pro

We saw claims that the Wii U Pro controller would sport an impressive battery life just weeks ago. That turns out to be true - Nintendo says its new 360-esque controller will last up to 80 hours on one charge. Not bad. Recharging the device will take 4.5 hours.

Turning on the System

It's possible to access your Wii U without even turning on the TV. The power button on the GamePad will enable the system, and allows you to access content without touching your TV. The best part - the TV Remote integration will let you then turn on the TV through the Pad itself. Pretty awesome.

But wait, there's more. You can also access the GamePad and turn on your Wii U through the controller's touch screen. Right within the remote interface is a button that says 'Play Wii U' - touch that, and your system turns on. Of course, you can also press the power button on the system itself - kind of how we've been doing it for decades.

The Wii Application

On Wii, you could simply insert a GameCube disc and access it through the system's main grid-like menu. Simple enough. Wii U's backwards compatibility is more complicated than that - the system appears to effectively boot into a mode dedicated to running Wii software.

If you're wanting to play your Wii Virtual Console, Wii Ware or original Wii software, you'll need to access the Wii application from your main Wii U interface. What's more, you'll need to use the Wii remote to navigate this environment, just as you did with the original system. It's also worth noting that WiiConnect24 functionality will not work.

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Wii U Accounts

We know Nintendo Network will have a role to play with Wii U, but we're still waiting for details on that. For now, we do know the system supports up to 12 user accounts per system, represented by Miis. Save data, game logs and times and 'other information' is stored for each account.

Transferring from Wii to Wii U

We've got a full article right here - First Details on Wii to Wii U Save Transfers - but here's the basic idea:

You can transfer your Wii save data, plus your WiiWare and Virtual Console games - and their saves - to your Wii U. Plus leftover Wii points, Miis and any other downloadable content. But you can only do this once, and you move all of your information from your Wii to Wii U using SD cards and an application you download to your Wii. It's a bit convoluted, but Nintendo says it gets the job done. Oh, and you need your Wii and Wii U simultaneously active and hooked up, so don't go selling the old system yet.

Read the article for more, and we'll try to do a video guide as soon as humanly possible.

Digital is the New Print

The era of the giant manual accompanying a system is over. Remember the 3DS's epic-sized launch manual? Wii U doesn't have that. While it does have some printed instructions, much of its 'how to' information is stored in a digital manual embedded in system itself, accessible through the home screen. It's an interesting move, but we're also seeing the games themselves take a similar approach. It's certainly easier than digging up a booklet you haven't looked at in months or years, we'll say that much.

There's going to be plenty more to talk about in the coming days and weeks as Wii U's launch approaches. We haven't really been able to detail Wii U's OS, and functionality like Miiverse and video chat aren't even activated yet. Plus we're hard at work on reviews, guides and much more.

Stay tuned. We're just getting started.

Rich is an Executive Editor of IGN.com and the leader of IGN's Nintendo team. He also watches over all things WWE, Resident Evil, Assassin's Creed and much more. Follow him on Twitter, if you dare!