If you are referring to a 1/4" hex impact driver, definitely go for it.
I held off for quite a while, but finally gave in to buying a 12v 1/4" impact this spring, it blows my old 18v drill away when it comes to driving screws, bolts etc. Much more compact, light weight, and you can kiss stripped screw heads goodbye, the impact action is much more resistant to rounding them out than the drill was. Throw in some 1/4" hex to socket adapters and it is even more versatile. I used it last weekend to disassemble a swingset/playhouse that was a handme down from a family member for our little girl. It made quick work of backing off dozens of 3/8-1/2" lag and carriage bolts, and 2 5/8" carriage bolts. Only had to break 2 free with a wrench beforehand. Completely reassembled on the same battery as I used to disassemble it.
I have both a Bosch 12v and a Craftsman Nextec 12v impact driver. Bought the Craftsman on sale for $40 just to try it out, was so impressed I stepped up to the Bosch version. Easily I'd say they are in my top 5 favorite/most used tools in the shop.