I upgraded 4 Mac from 10.13.1 to 10.13.2 today. Three iMacs & a MBA were done. Two iMacs have HDs & the third a Fusion drive. The MBA, with an SSD had been converted to the new APFS structure while the iMacs had not.
The MBA completed its update in about 8 minutes, the others took around 35 minutes. I'm inclined to think this is a benefit of the APFS.