Gosh,
@fisicx's points really put me off Windows 10.
@Bob I'd echo the comments that if you don't have a touchscreen laptop or particular need for Windows 10 then it'd be sensible to wait. You can claim/reserve your free upgrade now so you can always do it later, and simply not perform the upgrade yet.
In most cases the risks outweigh any potential reward at the moment, especially for business use.
The main reason to upgrade now would be if you have a touchscreen laptop running windows 8.1 for example, or for personal use if you particularly want Windows 10.
I was looking forward to upgrading (I have a touchscreen laptop with wacom digitiser for my personal laptop), however I'm unsure about driver support and the privacy/control points are rather disconcerting.
I imagine there will be be a big backlash and even EU anti trust cases brought against Microsoft if they go that far. If it gets enough media attention they'll likely do a U turn like they did with Kinnect for the XBox One.
I suppose they can argue only allowing Bing is acceptable if you're using their own Cortana software, but they certainly won't be able to do that for the Edge browser without some lawsuits coming their way.
Integration of services can be very convenient and useful but the walled garden trend is rather troubling.
Also why didn't they just make the desktop live tiles based? Who uses their desktop anyway? I would have thought that'd be a better way to integrate it. I haven't looked closely at Windows 10, but if people are still double clicking icons on their desktop on a new OS in 2015 then something's wrong in my opinion.