I still think that Nintendo should learn from Sony MUCH more.
Nintendo: 5€ for NES game and haven't encountered any sale, only for specific console so had to be rebought for handheld, from Wii to Wii U you need to pay upgrade fee or play worse version which requires booting up Wii mode.
Playstation: 5€ for PSX game (much newer game) with regular sales down to 1.3€, can be played with PS3, PSP and Vita connected to same account, cloud saving to move save files between platforms. For some reason isn't available for PS4 yet, but I would imagine them being free if they are bought in the past.
This is age where everyone plays with emulators starting from mobile devices and browsers, so you would think that Nintendo would fight againts that by providing better service with wide library. Even if they are strongly againts emulators they still do exist so it just seems odd they have decided to simply fall back from Virtual console.
Back to DS Virtual Console, wouldn't it be much more viable to sell those at 3DS eShop? Some DS titles are still relevant because of backwards compatibility of that system and there wouldn't be need for emulation when games run natively and DSiWare games are still sold as well.
If Brain Training was a proper DS Virtual Console title I'd be impressed, but they essentially split the Wii U GamePad screen in half, for which that particular game works well (since you'd be holding a DS sideways to play it originally, which was awkward). What I want to see is a DS game that, much like on the DS, has the top screen (TV) and bottom screen (GamePad) separately. It'd make some games really weird to play (think Sonic Rush), but let's be honest most DS games that would be fit for Wii U are puzzle games, visual novels, etc.
Well they could implement many scaling methods in there. DS screen isn't that big so having them side-by-side without flipping would also work, even though it wouldn't be exact 1:1 upscale.
When you said "proper DS Virtual Console title" it did make me think that Brain Training isn't that demanding DS title isn't it? Could it be that was only game they got to work without problems?