The SmartHub is ok, I notice a little lag in the menus but nothing that makes it unusable. I can see how a dual-core processor would make it faster. I tried using the browser, but using just the standard remote with the browser is incredibly difficult. If I want to look something up it'll be faster for me to use my computer in the next room. You can hook up a keyboard and mouse to the TV for use with the browser, when I get home I will try that out.
If you're looking at a good way to stream videos and music from your computer to your TV, the SmartHub's AllAcces does an excellent job at it if you don't have an HTPC. You have to install a program from Samsung on your computer first to share it with your TV. Most of the files I tried played fine on it, and I didn't notice any sound dropping out like I've heard someone else mention. I did have one .avi file not play that played fine through my HTPC, so not everything is supported.
For the price difference between the E6500 and E7000, you could instead get an Apple TV, Roku, or build an HTPC that would do a lot of the same things but better. There's some debate on if the dual-core processor will actually help the PQ of the E7000. I'm betting it won't help for normal content, but I can't wait to see some comparisons.