Not much bigger than a Switch with Hori Split Pad Pro:

Since the Switch with Split Pad Pro controllers is so much more comfortable in my hands than the Switch with Joy-Cons I'm looking forward to the Steam Deck form factor with enough grip for the palms of adult's hands.

Personally, I wouldn't mind a larger size.

I have big hands, so it's not an issue, the Switch's Joycons are a little small for me... Hence I never use it in portable mode.

The thing with the Steam Deck... It's not replacing consoles, it's just an extension of the Steam Ecosystem and PC gaming, it's unlikely to sell 50 million units or compete with the Switch.

To be fair, the Switch doesn't fit in your pockets either... Unless you are wearing baggy pants from the 90's that are 10x sizes to big, that you hold up with one hand, with pockets that stretch to China.

But that is okay. Just chuck it into a backpack I guess.

Yeah. I am just waiting on LPDDR5x/DDR5 laptops and next-gen mobile Ryzen before I upgrade my current Ryzen 2700u and 4700u notebooks... Should last me a year or two.

I don't spend big on notebooks due to how infrequently I use them, so I am happy running from decent integrated graphics and gaming at 720P for a few hours once in a blue moon.

This. The WiiU's display was small, bad quality and low resolution. The pad was big.

I didn't mind the ergonomics of it though, happily completed breath of the wild on it... But didn't use the handheld screen at all.

 I really wish they had a PDP Breath of the Wild backpack in the same style... Not keen on having a hand bag/messenger bag.

Uhhh... maybe, but if I was looking to carry my Switch around with me, I wouldn't be using that. 

Yes, it's on the large side. But I don't think that will hurt sales, because I don't think the target audience will care that much. Unless this is going to be stocked in Walmart and Target and sold like a traditional sort of thing, I don't see it as that big a deal (pun intended).

Right, I think some people are thinking of the Steam Deck as a platform in itself. I see it as a model of handheld mini-PC that aims for portability without compromising too much in terms of gaming performance. Like other PC models, it will probably have yearly (or biyearly) revisions and improvements. Its competitors aren't the Switch, but other handheld mini-PCs -- and there it is competitive on a price/compatibility basis. The new Aya Neo Next will cost $1300 - $1,500, whereas the topline Steam Deck model costs $649. Of course the Aya Neo Next will have better build quality and specs, but if you are somebody who wants a handheld mini-PC for a cheaper price the Steam Deck is a really good deal.

Handheld PCs never sold much. Seriously, it's not hard to understand what I meant.

And I don't need to watch previews to know stuff about the Steam Deck. I just googled it. With some games it can last longer, up to 8 hours, but with most games, especially more demanding games it's closer to the lower end at 2 hours, which is short. The OG Switch had a minimum of 2.5 hours, also to short. On my v2 Switch I can play a game like BotW for over 5 hours. Since the Steam Deck's battery life is shorter and it's pretty heavy it's not for me.

When I play in handheld I like to lie on my bed, it wouldn't be very comfortable with this thing.

ARM does what Intel'nt

Steam Dock will compete with SFF PCs or gaming laptops.

The point is it isn't meant to sell handheld or console numbers it's purpose is to sell the Steam library, also regarding portability just like when the Switch came out there were those put off by it's size but also like the switch it will mostly be played at home plugged into the TV.

I know what it's supposed to do. I'm just saying that it's unappealing to me and most likely won't sell much.

And before the Steam Deck, which company took making handheld PCs seriously on a big scale? And it kinda is because you weren't clear on what you meant...

Except the Steam Deck has power profiles and settings that one can tweak to increase battery life. So no, it's not so simple.

The last point I can agree with but I mentioned the weight as being as issue as well. For me it's not a deal breaker but I can understand why you would skip it because of the weight.