I have a Hitachi DS10DFL 12-Volt Peak Li-Ion 2-Speed Drill/Driver and probably used it 500 times in the past 6 months. It's excellent for light to medium jobs. With that in mind, I figured I would get this to handle any jobs it can't. The first such job was wall mounting a TV in which I was driving 3" lag screws into the studs. This tool was able to do so, but I felt like it was stuggling greatly. At the time I found myself wishing I had the 18v or a corded version.
For my uses, this tool is too strong for light jobs (compared to drill) and too weak for strong jobs- I would recommend the 18v instead.