As much as i want a surface pro/haswell surface pro - im really impressed by what lenovo is doing.
The yoga looked pretty sweet, but the model i tried out in the store was a little bulky. 13 inches imo is probably too big for something like this - at least until they start to implement super slim bezel's and thinner devices. I just saw that they are also releasing a yoga 11 inch, which will be 800 bucks, and looks like a very strong competitor to the surface pro.
heres the video:
http://youtu.be/NdEdihSAOSY
Only downside is that its a little bulkier, and youll have to rest it on the keys when in tablet mode, but when comparing to a surface pro (ivb)
+better keyboard
+keyboard is always attached - and available to use as a stand, laptop, etc
+cheaper (800 with keyboard vs 900-100 without)
+/-slightly bigger screen
-lower res (for me not entirely a bad thing - id rather play civ V at native lower res, rather than having to choose a low res on a 1080p display. I actually am OK with the low res on the surface RT on a device that small)
-not made by MS (not sure why i care - google ruined me)
-just found out it doesnt come out until june - which by then you really are just better off waiting for a haswell surface
I think either way, the surface 2 is gonna make this gen almost obsolete, but i think either way, i may just pick up something, and then sell it when haswell comes out. I think if both the surface pro and the yoga 11s were out today, id probably go with the lenovo.