I remember the SD to HD upscaling and it was basically rubbish, wasn't worth having. You just can't add information that isn't there, all you can do is blur the existing information together and simulate something in between, but it doesn't normally look very good. Actually the real question is what does the scalar do with 1080p content. Does it just draw 1 1080p pixel into 4 pixels of the screen or does it try and apply its magic and mix it with the pixels next to it and produce a blurry messy image?
Right now the standards aren't in place to do 4k properly in the living room. DisplayPort and PCs have just now gotten to the point of this working well without all sorts of workarounds and TVs aren't going to be worthwhile until they say they have the appropriate HDMI 2.0 standard in place. The 30hz 4k TVs are going to be just like buying a 720p HD TV was back in the day, worthless because everyone will eventually just get 1080p@60 and the same will happen on 4k (2160p) as well.