It's worth it.
1) The Picture is much finer and a lot less pixelation.
You can compare it with this video here which was shot on the old HD.
2) The Still pictures are far better.
3) A lot better LCD Screen which is easier to use and read
4) Sound is way better, a lot less wind noise
5) Burst Mode
6) More Options for shooting.
7) Much better Video and pics in lower light. The Old HD sucked at this
Much better under Water. The old HD was really bad under Water.
And yes the LCD Backpack works with it too
I am definitely happy with it. My old HD will now be used for the stuff where there is a real danger of losing it