Yes, I'm happy with my upgrade beacuse the SD material looks better than with my old Sky+ box and there is a bigger hard disk.
I only paid £199 for my box which as I was contemplating spending £100 for a bigger drive on my Sky+ box at the time was good value to me.
Is the HD material worth £10 - the jury is out for me. Personally, I don't see that much difference between HD and SD that I feel I must plan my viewing around the HD channels. So I could take or leave it.
When my year is up I will probably continue with the HD subscription but only because its boils down to just 33p a day rather than it being something I can't do without.