I’ve been attempting to use the whiteboard in Fibery more lately, since one of the teams I’m working with has used Miro in the past and I want to see if it can stand-in there in a basic way. Well, in theory it can. But it’s rather too clunky and quirky to work with right now, I think.
Here’s the thing: 15 minutes of experimenting should turn up plenty of issues to address. I could list them out, but I’m not sure I should bother at this point. That said, there are two particularly frustrating issues I ran into that I did record videos for, so I’ll share those, and maybe add more specific reports later.
First, there is some extremely annoying, inconsistent behavior with Frames. It seems there is some kind of “group” or “capture” functionality (or bug) happening with Frames where certain other objects on the whiteboard are the only ones that are “associated” with a frame. This means A: they are the only objects that show up “in” the frame when you save as image, even if you “send to back” and even though in the actual whiteboard view all objects appear to be visible. B: when you drag-move the frame itself, some objects move with it! But not all. This very easily results in lots of weird, unexpected realignments/shifts. Here’s a video showing some of the wonky behavior:
And then the thing where sometimes drag-moving a line with an arrow on one end loses the arrow. It seems to happen when you connect a line to an object, but I think it sometimes happens in other circumstances too. Here’s the video, hopefully you can find the common root:
This happened to me dozens of times as I refined my diagram. 
And I kind of get it, whiteboard seems to be a bit neglected in general, and it’s really not a core feature of Fibery. But… it can be just good enough to actually make the loss of functionality from e.g. Miro worthwhile for the integration you get, but only if it’s not unpleasant to use. Which it is right now.