I've used two of these pieces so far for my Jigsaw Fantasy line and have plans for one more. At $5 for this quality of art it's an amazing deal.
The only slight issues are with the license terms:
1) They're not properly copyedited, containing misspellings and poor grammar.
2) They don't allow any modifications this isn't something I've needed to do, but it is worth noting. (If you need to modify I'd recommend contacting the creator)
3) Again, not an issue for me, but there's a clause in there that might worry some midsized companies, disallowing use of this license by: "Wizards of the Coast, Hasbro, Alderac Entertainment Group, Games Workshop, Palladium...and any other mainstream compagnies to be determined by Shaman's Stockart". Depending on your company's size, you may wish to check beforehand.