The sx50 is an awesome camera, just as great if not a tad better than the sx40 which I thought was hard to beat to begin with.
The extra zoom, higher res LCD and a tad faster focussing make it worth the upgrade to me. Also I love the different compression/quality modes i.e. fine/normal JPEG (the sx40 lacked this, and the LCD was of low res quality making it hard to tell if a picture was focussed properly after it was taken and viewed in review mode on the LCD).
Nonetheless I would have no problem grabbing my old sx40 on any given to day to go shooting with.
Of course it wil lbe interesting to see what Canon has lined up for the predecessor of the sx50.