I think the Yoga is an ideal device from an ergo-metric standpoint. My cMBP is a tank (relative), my iPad 3 too heavy to hold comfortably while relaxing in content consumption mode; and the cover does not allow for the perfect viewing angle.
I want simplicity in my computing environment; one device, one OS, no external peripherals (e.g., keyboard).
The Yoga has all the above, and with the 360 degree hinge, I would be able to consume content comfortably in any position (even laying flat on my back in bed with the Yoga on my belly).
If only that were true
It is huge (13"). It weighs more than the 13" MBA. It weighs almost 3x more than the iPad. It has only an 8 hour battery (compared to 10 with the iPad). It seems like a Frankenstein device that is a horrible compromise in every respect.
But, maybe I'm wrong! That is just my impression, and it reminds me how great it is not to have everything stuck together. I love having the keyboard separate, so I can read when I want, or work when I want, getting the best of both worlds.