I have had two Draper ones, of the type Bob linked to, over the years. Both have been very good, but you do need good quality bits for them (I think the shank size is 3/8" hex* rather than the normal 1/4").
I used to use a normal but large hammer, on occasions a 2lb lump hammer, and it is necessary to pre-tension the coil spring, twisting it to take up the slack. It is very handy to have the 1/2" square drive shaft too.
I have one more, with a set of long shafts and a narrower handle. It's nominally cheaper and probably Japanese manufacture (it's old!), but still gets a lot of use because of the longer reach. The handle end of the shafts has a "tenon" that fits the handle. The mechanism in the handle is retained by a fine- pitch right-hand thread holding the two parts of the handle together. Years ago this came loose, and I have never succeeded in keeping it tight since, so it tends to unscrew itself at crucial moments.
They are a lot more useful than you might think, because of the control you can use, and that they don't tend to cam out of screws in good condition. That said, I find my powered impact driver with a diamond bit fitted works very well. But it is hard to be gentle and too easy to snap screwheads off.
I have, however, often made the novice mistake of using one last, rather than first, after I have already damaged the screw's head with a slipping screwdriver. If you do get one, reach for it first, if there is the slightest possibility the screw won't yield to an ordinary screwdriver!
E.
*That Draper page says 8mm, but mine is very old and probably imperial.