Since I was a child, I've had almost every version of Nintendo's handheld system, starting with the original Gameboy. I still have many of them such as the Gameboy, Gameboy Color, Gameboy SP, DS, DSi, and 3DS XL.. However, I am currently happy with my...

This sounds pretty rad. I owned an original Gameboy back in the day, but never owned a handheld system after that. I think I was taking myself too seriously.
But now, after owning a Wii U, and playing Mario Kart on the controller whilst having something else on the TV might have convinced me as to how great handheld gaming can be. I don't anticipate getting one right away, but I no longer rule out buying a DS of some form :)
(And what's funny is that the Wii U controller was the part I thought I'd hate about it. I do prefer playing games on the tv with Pro controllers, but the Wii U controller is super handy for multitasking)
Well, it's been a long time since a Nintendo console and handheld system were able to function together. The Gameboy Advance was able to be connected to the Gamecube and used in some games (like Animal Crossing). Recently, that functionality has come back. In Super Smash Bros, you can use the 3DS and Wii U together, or at least transfer data from one system to the other. Actually, now that I think on it, I think the Wii and DS versions of Animal Crossing also had similar functionality.
At first, I thought the Wii U gamepad was a bit bigger than I expected, when it used it at the kiosk in Gamestop. Since then, I've gotten used to it and I like it a lot. I now turn on the Wii U using the gamepad and I use the touch screen to select the game I want to play and log in under my profile (instead of my son's). I've been playing Hyrule Warriors a lot and don't usually use the touch screen in game, though. I did try to co-op the game with my son, which put him on the TV and me on the Gamepad. That was a bit disappointing since I'm used to playing on the TV.
I'm glad you're enjoying your Wii U.
I've enjoyed the amiibo functionality that's on the Wii U gamepad. I think it's interesting that it came with that functionality before the amiibo figures were released. Every day I use my Link amiibo and my son's Mario amiibo to give me something in Hyrule Warriors. I usually get a weapon using the Link one and just about anything with the Mario one. Sometimes Mario gives me gifts that aren't that great, such as one day I got 1 rupee.
I've used the amiibo figures once on Mario Kart 8, I can't even really recall how that functions, I think it just unlocks Mii costumes. I've used my Link amiibo in Super Smash Bros. on the Wii U a few times, usually putting us on a team. I still have hardly played Super Smash Bros. on the Wii U, but I'll probably play it more when I'm done with Hyrule Warriors, which should be soon. After that, I'll be waiting for the Majora's Mask DLC.
Nintendo also announced new amiibo figures coming out soon. Toad is among them because he has a new game (which I think is already out). The article (link) I shared also states that more Marth figures will be coming out along with a new Fire Emblem game (for the DS, I believe).
Hmmm no charger huh? Maybe they figure everyone already has a few previous DS systems?
Hey Greg did you see if this would be backwards compatible with regular DS games too?
I found a link explaining the lack of charger for the new system. It states:
Nintendo responded to our request for comment on why it was decided to leave the charger out of the box. According to Nintendo, it was a measure designed to save costs for consumers who may already own a 3DS or DSi system: "New Nintendo 3DS XL uses the same AC adapter as any Nintendo 3DS or Nintendo DSi system. Rather than raise cost of New Nintendo 3DS XL by charging consumers for a component they may already own, we are giving them the option to only buy if they need an AC adapter." http://www.ign.com/articles/2015/01/14/new-3dsxl-doesnt-include-charger-here-are-some-options
From another Google search, it seems that it will definitely compatible with all DS games, with some exceptions. See the following link: http://en-americas-support.nintendo.com/app/answers/detail/a_id/324/~/can-i-play-nintendo-dsi-and-nintendo-ds-games-on-nintendo-3ds-family-systems%3F
Great, thanks Greg.