so far the convertible tablets out there are a bit disappointing. They're either have minimum power, or when they have maximum power (maximum will have only Intel HD Graphic 4000), they only have 4.5 hours battery life. Even the one coming next year, the Microsoft Surface Pro has 4 hours battery life.

So it's either 8 hours battery life with minimum power or 4 hours battery life with maximum power.

ultrabook different. powerful ultrabook can easily last for 8 hours, but heavier, thicker and not convertible.