How do you know they nailed it in terms of performance? It's running on a Core i5, on which even Vista or Windows 7 runs well. We don't know how well it will run on Atom or ARM yet, which will be the "tablet optimized" chips, with higher battery life. The Core i5 will give 2 hours of battery life, especially in such a small package compared to a notebook.
Acer isn't exactly known for brilliant power engineering, so a better vendor could likely do better. But this also wasn't exactly a high-powered chip, either. So this is probably a plausible baseline for battery usage in Win 7.
They need to beat this by quite a bit in Win 8, or the tablets will be a tough sell.
