It CAN work, but there are some caveats.
First I've literally had a 50/50 success rate with drives. Kingston, Sandisk don't tend to work because they have bundled software. Also ones with big LED lights have problems. I've had the best luck with Generic drives. So be prepared to experiment. I experimented with everything from 256 megs to 8 gig and found no consistent brand or size that always worked.
Second, the photos have to follow a very strict naming convention. You need an upper level folder named DCIM. All the photos must have 8 character names. DSC_3455 for example. If your photos are straight from your camera, you should be good to go. If you've edited them, you need to edit the names as well. Put those photos in the DCIM folder and connect the drive.
If your Pad sees it, it'll open the photos all and thumbnails of the photos. You cannot view more than thumbnails off the drive. To see them bigger, you must import them.
Once you import, pay attention to the dialogue boxes because it'll offer to delete the photos for you.
So it can work, but you need to be ready to twiddle and tweak. If you have a memory card it'll work much easier.