Tomo,
I havent had much of a play on this unit, but when I did, and from what I have seen / heard the side scan the unit provides is a bit of a gimic - a little like the 3d mapping the new plotters produce.
I was a little sceptical as a 'proper' side scan runs into many thousands, like fitted to commercial trawlers etc. I think it is a start, and in coming years technology will catch up allowing us ordinary folk such technology.
For a proper unit look here: http://www.olex.no/
... then get your wallet out!