Surface RT's Achilles heel
no it isn't the lack of Retina Display or the app count. It's the fact that it advertises itself like a laptop, but you can only use it that way on a hard surface like a table. Notice the Surface ad showed the guy using it on a table, not on his lap. Also the ad briefly showed people holding it in portrait mode, but that was for kicks. 16x9 is too narrow for portrait mode.
* doesn't work as a true laptop
* portrait mode is virtually unusable
If you're ok with that, then the Surface RT is a good buy.