What sort of work do you do Steve – and what machinery do you already have?
Although hand and power shapers both work on the same principles – they are different in nature to my mind. I use my hand shaper for smaller jobs (instead of hand tools – like files & hacksaws etc) as it is much more accurate than my hand work and gives a better finish. But although it is possible to remove large amounts of material with the hand shaper – it is tedious to do so – and I have other machines that are better.
So for smaller work (or where you simple want to "finish" work to a good standard) the hand shaper is a very useful tool but it is generally no substitute for a powered tool (whether that be shaper, mill or lathe). It can however give very good results and is quiet in operation (so good for indoor use – with permission from Herself)
So if your work is of a larger nature (or you already have a good mill) then a hand shaper may not be very useful to you. But if you are any kind of small scale modeller, then the hand shaper can be a very useful and convenient tool. Like many things discussed here, the context is important.
Regards,
IanT