The Automatic Document Feeder takes more than one sheet at a time when scanning. I found the same defect with 3 4101fdws I purchased and replaced over the course of a few weeks.
Print quality was terrible, splotches everywhere. Had to se for heavy paper to avoid the splotches, which added to print time. Didn't have 2 weeks and had to send back as document feeder malfunctioned and wouldn't reset.
I purchased this printer/scanner for my home office. I love the size as it fits perfectly where i intended it to be. It runs smoothly with minimal noise when it prints. The quality of the copies is HP perfect.
Printer is very nicely designed. Functions well. Lots of improvements over previous multi-functional printers. Nice and compact without trays jutting out. The touch screen is nice addition. The neutral white color makes it look nice also. One suggestion for improving it: find a way to make the fan quieter.