So now that the system is out, has anyone taken it apart yet? And do we now know how much more powerful it is than the Wii U?

Hard to compare directly but I think they are closer in performance than many people realise but with the Switch having a definite advantage in most areas. Maybe the Chipworks images when available will reveal some secret sauce but going by game performance so far the Switch is looking extremely under-powered for a 2017 release.

Aren't most Launch games like that though? 

Still unknown but the pessimists seem to be winning.

More powerful than Wii U but less powerful than XBO or PS4.

Completely subjective. Switch is providing an amazing gaming experience through a truly unique platform. Something no other system can offer. 

A hybrid car is only extremely under-powered for a 2017 release if you only consider sports cars. But that ignores the separate and unique experiences each platform offers.

This silly comparison can only exist between Sony and MS. Nintendo stopped playing the power game with Wii and who the hell wants another me-too system offering the same exact library? Sure, more content is always great, but not if it sacrifices Nintendo originality.

To answer the OP directly, Switch is what we've known since around Q42016. Its a system that is a few times more powerful than WiiU while supporting all of hte latest technologies enabling the same developer tools used by all gaming companies. It is around 1/2 of the Xbox One.

What's more important is what type of content it will have? It will surely have anything you've seen on past Nintendo consoles (portable or home) since Wii. Based on the support of all 3rd party development tools which have deep scaling capabilities, I'd also expect to see many/most of the yearly titles such as fifa, madden, cod, etc... which all tend to launch near the end of the year. This will be show as right/wrong come E3.

Nothing official as far as I know, better than the Wii U but weaker than the PS4 and XOne

I'll stand by my extremely underpowered for a 2017 release. The comparison was with another home console the wii u. Comparing it to the Vita is a different story. 

It isn't half the power of the xbox one.  Ultimately it has a memory bandwidth of 25.6GB/s considerably less than 360 and PS3 but more than wii u which dictates how much data can be processed by the system. 

As has been pointed out many times the Switch is extremely easy to develop for using established hardware and its performance level is likely to remain fairly consistent.

As more games are launched we can get a better picture of its performance level but looking at its spec and looking at the current game performance level there are no surprises.

However totally accept the Switch is not about its performance level it offers something different but its important to understand as a home console it is incredibly weak a  generation below ps4 and xbox one which are now pretty much budget consoles. As a portable console it represents fantastic performance a huge upgrade on Vita.

It's extremely well powered for a mobile device.

FAST RMX might give a hint actually. Zelda art the same time gives a hint where Switch has it's issues.

Just a bunch of ports from Wii U games with minor adjustments. Nothing really helping having a concrete view.
Yes Zelda has framerate issue/looks pretty much the same then the Wii U version.
And it's a lazy port. So can't say.