What it looks like would depend whether it got infected or not. If infected they could be red, swollen and full of pus. If not infected they would be healing up albeit that the stitches or steri-strips would still be in (not sure that they would necessarily be stitched, given that each individual cut won't be that long - for smaller wounds they use glue and steri-strips, but check with an A&E doctor how it would be treated) The glue would reduce the likelihood of scarring.
Also, if the pads have been nearly sliced off, doctors may remove them altogether rather than trying to reattach them, as the presence of dead tissue massively increases the risk of infection and possibly gangrene. This would depend on the condition of the nearly-sliced-off tissue. In this case there'd be no stitches as there's nothing to stitch up. The exposed surface would be initially protected by a blood clot then the skin will start to heal under the clot. It's unlikely that the fingertips would look ever normal again after this.
A more pertinent question IMO would be how much functionality he'd have in his hands. The fingertips are very sensitive and that's not just in terms of this injury being extremely painful (he'd still be in pain a week later) but also for the hands to perform their functions - think about if you pick something up, your fingertips will sense how much pressure you're putting on the object and what that object feels like (e.g. if it's soft or hard, rough or smooth) and this gives feedback in terms of how you hold the object. Instead of this sense of texture and gentle pressure, he's going to get pain. He's going to struggle to pick anything up, and therefore do anything. I don't know how long it will take before it's healed up enough for him not to be in pain all the time. Probably a week or two, without infection. Suffice it to say if it becomes infected the pain will be much worse, i.e. to the point that he won't be able to bear touching anything at all, and it will take much longer to heal up.
