I am assuming that you are looking at SV6.
I have just traded a 2008 MY09 SV6 Manual on a 2011 MY11 SV6 Manual.
The following differences are already evident:
The engine is much improved, being smoother, more responsive and quieter. Can't comment on fuel economy yet as too early, but expecting better.
Gearing is improved. The gearing on the MY09 was too tall, running 1,900 RPM at 110. The MY11 sits on about 2,100 at 110, and has much better reserve torque for overtaking and hills.
Instrument cluster is a big improvement. My aging eyes struggled with the small numbers, white on grey lettering (car was silver) and horrible red lighting.
Infotainment system is a plus.
The bluetooth is a big improvement if you have a compatiable mobile. I bought a Nokia 2730 pre-paid from Optus at $44.10 including postage, and it works a treat.
Standard dual zone climate control aircon is also a big plus.
My car also has individual map lights in the front and a rear centre armrest. These do not appear on the "standard" equipment list, so I am not sure that they are universal.
And finally, the Red Plate special for a manual MY11 SV6 has been reduced to $34,990 drive away - see
Home - Holden. Go better..
Having lived with an MY09 SV6 for 2.5 years and now upgraded, I would recommend the MY11 if you could afford it. I think that it is worth the extra.