These Sandy Bridge-based notebooks have some advances, the most important ones being much better energy consumption (therefore batteries much more lasting) and more powerfull embedded GPUs.
Where have you seen reviews indicating "much" better energy consumption on Sandy Bridge? From most of what I can see, they're not that much better than the Core 2s were, and mostly just gaining ground back that was lost by the Arrandales (eg mobile Nehalem, the current shipping generation of mobile i5/i7).
The biggest must-have selling point for Sandy Bridge is at the high-end, they are the first really useful mobile quad cores.
At the lower end, they're a good bit faster than the current Core i3/5/7 but not a huge generational jump in speed the way the i3/5/7 were over the Core 2 or the Core 2 was over the older chips (Pentium M and Pentium 4-M.)
The faster integrated GPU is nice, and I'm sure it will sway a few more people off discreet graphics, but in general the current i3/5/7 integrated GPU is fast enough for general use... and the new ones will still not be powerful enough for gamers (and people who need 3D for professional apps)