Just got a DCR-150 see a few shots here
http://www.talkphotography.co.uk/forums/showpost.php?p=2923009&postcount=91
I don't have the 250 (8x mag) to compare but found the 150 (3.8x Mag) to be a great walking around accesory. Shot 1 of mine is at 70mm and only cropping out the vignette, Shot 2 is a tighter crop - but they show a reasonable example of what you can get.
My guess at the moment is that the 150 is a great walking around lens and the 250 is for those with perhaps a little more patience and a love of bugs.
Focusing is the hardest part so prepare for a reasonable miss rate, but there is something really pleasing about Macro photography (says first day macro user!)