Considering its the future direction of Windows, not taking the free upgrade would be rather foolish.
However, waiting until the 28th July 2016 before taking it, in order to let them iron out all the inevitable teething issues is probably not a bad idea.
I agree with both your points here.
IMO W10 was a good bit quicker and more efficient than 8.1 and this was testing in a VM as well as seeing it on a friends laptop.
I think they are making a good move with the UI. Yes w8/8.1 had complaints regarding modern UI but now they are appealing to modern UI lovers and legacy users with a nice blend.
For me, I got used to modern UI but will still be using the new start menu in w10.