I have had a SKY + box for about 2 years now and doubt that I could easily go back to life without it.
As has been mentioned it totally changes the way that you watch TV the only problem is that the SKY planner is only a week in advance.
The box I have is version 1 so only had a 40Gb hard drive in it, which gave approx 20 hrs of recorded TV, I installed an 80Gb drive in it and have had no problems with it at all and doubled the recordable capacity for the sum of approx £40.
Given that your box is relatively new this might not be something that you want to do while its still under warranty but I know that you can upgrade the later versions to 120Gb drives an perhaps higher so it maybe worth looking at.