If you're a professional who uses InDesign all day, you're going to be sorely disappointed in Publisher. It's got a lot of really nice little features, (like being able to adjust the width of column guides individually) but overall it's more of a "Apple Pages Killer" than an "InDesign Killer."
Way too many clicks/mousing to do simple things; such as what you have to go through to simply make a text frame background a color.
I Spent 20 minutes or so trying to find a way to adjust the inset of a text frame and never did find a way.
Speaking of text... hitting the T key actually activates the art text tool, not the text frame tool. You have to hit the T key twice to draw out a text frame.
Deselecting a text frame requires you to click outside the text frame before you can switch tools instead of just command clicking it like you can in InDesign.
Like I said, there are a ton of cool little features in it, but for those who use InDesign day-in and day-out, it just isn't there yet. It's missing a LOT of important/powerful features, too.
Of course, it's a beta for a 1.0 release. InDesign wasn't perfect at 1.0 either... but it was miles further along than Affinity Publisher is. I'm really looking forward to seeing how quickly they can implement features.