By all normal standards it's a very good concrete floor - dry, and perfectly smooth and level for walking on. However, a long straight-edge reveals some very gentle ripples in height, maybe 6mm maximum variation over 1 metre.
Will this be tolerable? I don't have a feel for how well the boards will follow the contours of the floor - especially in open areas where they won't be weighted down by furniture, but will be walked on.
There may be some limited areas that would benefit from self-levelling compound, but there doesn't seem much point in covering the whole floor, since that would probably introduce more ripples than it solves.
Obviously this is all to avoid the nightmare scenario of a floor that has been glued into a solid sheet... and then sags or creaks underfoot.
Any advice based on practical experience would be very welcome.