Internal SATA vs External USB 3.0

Can anyone tell me the draw backs to moving my Photo folder off of an internal SATA drive and onto an external USB 3.0 drive?

Well external hard drives are known to fail. We have 3 in our house (Seagate 500Gb, Mybook 500Gb and western digital 320Gb). Both 500Gb failed. Thanks God the pics on those drives were 3rd back (yes we have 3 backups ).
Get an internal drive or two. They are cheaper, more reliable and you can set them up in RAID to make images of your primary disk.

All harddrives will fail

In most cases an internal drive will be faster. (But I don't know for sure in the case of USB3)

My last drive failure was inside an HP desktop computer which was less than 6 months old.
The previous drive failure was NOT the HDD itself, but the cr*ppy interface electronics in the external USB unit; I pulled the HD out and put it into a docking unit and it worked just fine.
The previous HD failure before that was an internal unit inside our daughter's college laptop, which was about 1.5 year old when it failed.

Just because you have a USB 3.0 drive does not mean you have USB 3.0 speed. You have to have a USB 3.0 card in your machine, etc. Also, many of the existing USB 3.0 systems are not meeting spec yet so the true USB speeds for the most part are not being seen. USB 3.0 will be 10x the speed of USB 2.

I have a USB 3 card in my desktop. I currently use a Seagate 3TB USB 3 drive for my backup. I also have an enclosure that is USB 3. I was thinking of putting a fast drive in there and use it for my photos folder. Thoughts?