It's not too expensive. It's actually a little cheaper than I expected considering proper tablets usually cost 2-2.5X as much while lower end tablets are on par with the Switch.

Comparing it to a home console is apples and oranges, they're two different types of products. It is why tablets are generally much more expensive than desktop PCs with equivalent power. Switch is a tablet console that can be played like a home console.

I still have to wonder outside of core Nintendo fans and Japan how much appeal that concept has. 

It's inherintely a hardcore feature really, it assumes you like fairly complex video games (talking Wii/PS3/360 era graphics with physical controls a smartphone can't provide) and cannot leave the house without having those games to be able to play with you. 

It will be interesting to find out I guess. 

The other issue is push comes to shove, which device do people prefer, this (Switch) which only plays games basically or a tablet which can play movies, music, have books, surf the web, play games, take photos, do all the social media stuff, etc. etc. 

It's a new thing, it might fail, it might sore.
There have been other companies that have experimented in this realm, but Nintendo is the first major stab at it. If the Switch is successful, then I predict this sort of console will usurp traditional home consoles as the top dedicated dedicated gaming system form-factor within two generations.

The ironic thing about some of these Sony and MS folks looking down on the Switch as having outdated tech, is that all signs are actually pointing to the deticated home console becoming a thing of the past in the not too distant future. The next generation (post millenial) is being raised on a culture of smart devices rather than merely TV, and seamless/convenient entertainment on the go. Adults (particularly millenials) are also turning more to these devices in a increasingly fast-paced and demanding society. I have two cousins in their early teens and I see them glued to their tablets/moble phones far more than using the TV set for either playing games or watching video. Nintendo is gearing up for this future with the versatility and portability of the Switch. The TV set is slowly becoming old news, or at the very least, equal to smart devices in terms of relevence, and unless MS (and epseically Sony) adapt, they may end up being the ones being left behind in the long term. 

If 299 for Switch is expensive, than Wii U, for 350, was what?

In Europe we are paying 329 for it.
More than we hoped for, but hey, it's not 400 or 500 with just better visuals.

What i have a problem with is game prices. Zelda is selling for 65/69€. Now, that's expensive!
And i assume that other games will follow suit. And that's the worrying part: mobile gaming is taking over and the games industry response is raising games' prices?

If you have a device that can do all that stuff, why would you buy Switch to do the excact same thing? The point in portability isn't just to have your console on the go, but to take it with you when you take a shit or put kids to sleep or play games on it at the same time others are watching TV. 

I believe Nintendo emphasised the fact, that the majority of handheld console owners play them only at home.

If the mobile games are free or can be bought at pocket change, I don't think you really can reasonably expect 40-60€ games to compete the mobile games with price. All you have to do is make games people see worth buying (first and foremost, this is fighting disinterest).

The reason it's too expensive & is a problem is that Nintendo are desperate for sales at this point. Here in the UK if the average man saw on Amazon that you can get a PS4/Xbox One for £218 or a Switch for £280, it's not a choice. Nintendo need to be worried about that.

You're saying the reason Nintendo made the Switch "too expensive" is because they're desperate to sell more. This doesn't make any sense.  -___-

People aren't saying the Switch it too expensive for YOU. You don't need to justify why you're going to buy it.

Nintendo needs a low price to penetrate the casual market, and I think $299 is far too high. That's not even counting the accessories. The price is even more ridiculous in the UK at £280. That's a whole £100 more than the Wii when it launched.