I have had a more thorough look at the map tool and I was pleasantly surprised. I ran an encounter, without players, created a campaign, pc characters and used the encounter builder to create the encounter and manage initiative.
The maptool is pretty basic but with a map with a grid I would say workable. If one could label the npc token it would be quite serviceable.
I must actually try it with actual players but as a lightweight tool it shows promise.
The biggest gripes I would have are:
Token selection it should automatically filter to monster from sources one already owns (The encounter builder should do the same)
One should be able to drag encounters onto a map or prelink encounters with maps.
It is not that difficult to download maps from an adventure on D&DBeyond (I tried with the free version of Lost Mine) and upload it to the VTT.
I honestly have more issues with the encounter tool than with the VTT as it stands or even with its proposed features.