Firstly, you can't add any more RAM to it. This turned out to be a BIG problem for me as I handle a lot of fairly huge RAW files in Adobe Lightroom.
Then there's the fact that it actually spends 95% of its time docked to my Studio Display and using the BT mouse and keyboard which fuck out all the time.
And the battery life isn't as great as people make it out to be. If I am on the road, which is basically never, then I'm lucky if I get 4 hours out of it.
So I thought sod it, why shouldn't I just have a proper desktop instead which solves all of these problems. I looked at the M2 studio, went pfffft at the price, and threw together a windows desktop. I've got hard wired keyboard, mouse, ethernet and headset and I can throw another TB in it or double the RAM to 64Gb for less than $100 each.
And Excel isn't a piece of shit on it.