I tested times with my Transcend USB3 Stick (32 GB version) the same thing:
Copy 1.5GB file to the stick: about 23 sec (ie about 2 minutes less!)
File copy back again to the computer: about 8 sec
And then times with 'nem Verbatim Mini USB2 Stick (!):
Copy 1.5GB file to the stick: about 2:38 min
File copy back again to the computer: about 43 sec
Since you are allowed now decide for yourself whether you can call it USB3 or will you spend the money for it.