Depends on what you want really.
If you watch a lot of TV then Sky+ is a fantastic idea and really improves your viewing habits.
Also remember that SkyHD boxes are Sky+ in that they can record the same way.
As for getting SkyHD - well thats a bit of an argument at the minute. I don't have it, but the number of HD channels is very low and has not increased since launch. So you are paying a premium for a bit of football, the odd film and then countless repeats on DiscoveryHD.
And I have seen a lot of arguments on the net about the fact that the HD service isn't quite up to scratch and some of the broadcasts are not much better quality than SkySD. In fact the BBC HD channels have lowered their bitrate recently - which makes a mockery of the nonsense that is being sold to the masses.