How smooth should be the refinished (3 finish layers) hardwood floor surface? Is this normal?
The floor looks good and the finish is not fully filling the wood grain. This wood has a pretty deep grain - oak I assume. This is more eo be expected from a water borne floor finish. Waterborne finishes are a more "natural" look compared to the old school polyurethane finish- which is still very widely used.
We often will pay the finishers to do an extra coating when we have floors done and it does help but it is all just preference.