Scanners - e.g. Canon - will scan at at least 1200 dpi which is good, especially if you gently lay several coins on the glass before scanning.
Pros of them: the coins are absolutely in a completely flat plane and they're easy to set up and use, and attached to your computer.
Cons of them: the resulting scans are dismal for lustre, and can be very flat, though you can lift them in software.