i have one and according to CDSpeed it stinks, maxes at 8x on most CDs however a very few do get up to the 48x the drive is rated for (these are really 48x drives, not 50x):
Product : 50X CDROM
Firmware version : 1.10
Buffer size : 128 KB
Maximum read speed : 8448 KB/sec (48 X)
Read CD-R : yes
Read CD-RW : yes
Read CDDA : yes
CDDA accurate : yes
Read R-W : yes
gathered from the "Drive Check" feature in CDSpeed.
copying CDs to the hard drive stinks, the CDs i've copied take ~10 minutes to copy to the hard drive, which is approximately the 8x the CDSpeed reported.
however, for the price (free) I can't complain, but I wouldn't pay over $20 for this drive.