Indeed - command line is the best way to determine:
run this: pgpwde --status --disk 0
This assumes you're encrypting disk 0.
Itll output something like this:
C:\Program Files (x86)\PGP Corporation\PGP Desktop>pgpwde --status --disk 0
Disk 0 is instrumented by bootguard.
Current key is valid.
Whole disk encrypted
Total sectors: 625137538 highwatermark: 625137536 reserved start sectors: 2
Request sent to Disk status was successful
Leave it a few minutes then run it again. Compare the high watermark figure. That is literally the progress of the encryption. When it equals total sectors, its finished!