There can always be a negative side to purchasing a short-sale as an investment.
It’s possible to pay more than what the property is actually worth. Most of the time a short-sale happens because the home owner is upside down on the loan. However, just because the property is listed at what you think is a low price doesn't mean you're getting a great deal.
Normally these homes are sold 'as-is, where is', In this case, if there are hidden defects within the property (ie: unstable roof, termite damage, or appliances are worn out) that start showing after the deal goes through, you as the new owner, are the one who will be picking up the tab of repairing and replacing.
It could also take months for the lender to actually accept your offer, then…