I used it. If you bought a business item, you could take 10% of the purchase price off your income tax owed. Of course, that reduced the amount you could depreciate by 10% of the purchase price of the equipment. Essentially, it was bonus accelerated depreciation.
A few years ago, I bought solar for my home and took a tax credit on that. About the same thing, only I couldn't depreciate the solar. Had to settle for the tax credit only.