I can give you my opinion, as I've owned both of these; first the NX700 which I unforunately had to return, and now the EX700, which I'm keeping and will be demoted to a bedroom TV in a few months when I buy the new led-backlit Sony HX909. (a lot of money to spend on TV's, i know, but I held out on upgrading any TV's for quite a few years until now)
The NX700, while a really great looking TV unfortunately has a number of unnacceptable flaws, which given the higher price, cannot overcome the really cool 'monolithic' design. I was really disappointed in Sony with this TV, I'm hoping the HX909 can restore my faith in the brand.
The viewing angle is actually worse on the NX700 than the EX700; on the EX700 I think the viewing angle is actually pretty good, but the NX700 it was just ridiculously bad, especially for a supposedely high-end TV.
For the first HOUR of operation, the NX700 makes failry noticable cracking or creaking noises AND for the hour after the TV is turned off. (which is kind of suprising given that the TV does run impressively cool). This appears to be because the back-construction of the 'higher-end' NX700 is made of cheaper plastic, but the back of the EX700 is metal.
One flaw that is common to both TV's is the so-called 'cones' issue. In my opinion it is pretty minor, but still kind of frustrating; this issue can only be seen when there's a completely solid color at the very top or very bottom of the screen (such as a blue sky). It appears as three triangle-shaped 'cones' about an inch tall or so. Even when there is a solid color, you kind of have to look for it; it's not so bad that it obviously stands out. When there's not a solid color, there's no way you'll see it at all. Exspecially given that my EX700 will be demoted to a bedroom TV in a few months, I'm OK with this flaw on the EX700, but when it was on the NX700 which was supposed to be my main TV for hopefully at least a few years, even though minor, I thought it was unacceptable, especially with the other flaws it had.
Of course the design of the EX700 isn't as cool as the NX700, when I first got the EX700 after having returned the NX700, I was a little underwhelmed since the NX700 is so cool looking and the EX700 is a pretty basic design, but now that I've had the EX700 for a month or so, I'm used to it and I don't really think about it.
As far as I'm concerned, the choise is a no-brainer, go for the EX700, it's actually a little cheaper and substiantially better; definately better viewing angle and no annnoying creaking noises, all you give up is the cooler monolithic design.