Both my 5 year old son and I (34) love this sonic. The sound and light unit is nice and loud, unlike some of the earlier sonics. But the real fun is the 12 separate units. Putting them together in any order you like (as long as it's emitter, control, handle and pommel) lets you customise this how you like. You get the 11th dr's plus 2 never seen before sonics. There are quite a few sounds to discover and mess about with.
I hope this is the first in a series so you can add and collect more to mix and match. If so, then I hope the sound unit would have more/different sounds. And there could be a more "mechanical" element to the handle - like it slides up or a click wheel or something.
That aside, my son gives it a big thumbs up.