I own the version prior to this (late 2010, this appears to be mid 2011)
Mine, which I think is fairly inferior to this, handles an external display and runs my workstation at work. I do work on my computer all day at work, handing RDP connections and about 10-15 tabs open in Chrome, streaming music, all day.
When at home, I do watch TV shows on the internet on my computer. It works fine enough for that, although it is about the max of what it can handle.
The battery life on mine (again, which is 1 gen older) is better than the $300 netbooks that were out at the time (I had one prior to owning this), but not at the same legendary level of the ipad. You will probably carry the charger with you. However, the standby power claim, as well as the quick start claim, are absolutely true.
The display is amazing, well above average in any laptop. The cost of this device compared to other computers comes entirely from the quality of the display (it gets very bright), the price of the SSD, and the quality of the design of the machine. It is solid metal, not at all flimsy, and if you've never used a mac touchpad, you'll love it.
Bottom line: lots of PC users who really don't know anything about macs blow this thing up for price vs tech specs, but at this price it is worth what you pay for. Sure, the processor+video card+ram is way underpowered and you can find better for much cheaper anywhere, but there is more to a computer than the guts. That's what you get in a mac.
If you're thinking about using a virtualizing program to run Windows 7 or something like that, stay away from this. It doesn't have the stuff to do anything like that.