I have one as well - the only "Smart Ap" we use regularly and really enjoy is Pandora and we use it quite a bit... Its nice for when friends are over or one of us is cooking.
We also use Netflix through it as well which works nicely and now we dont have to turn on the Playstation 3 for Netflix.
We also downloaded the Red Box and Blockbuster apps, but have not used them yet - might be nice to get some of the newer releases without having to go to the supermarket to rent one... we will see.
Lastly, I have a Samsung Galaxy S3 phone that 100% integrates through the Smart Hub and I can send any pics or movies or music from my phone right to the TV - it also lets me use my phone as a remote. Really really awesome to **** around with my wife when I'm in the bedroom and she is watching TV
Surfing the web is a joke as of now - when they include a wireless keyboard & mouse, then we will see.
Regardless if you use Smart or not, your TV has a better processor that makes the image quality much better than the same Samsung without Smart capability - so no money wasted if you dont use the actual aps...
As for the OS - its Samsung proprietary software - not Android or anything like that.
I wouldn't worry about the hacking.
I would give Samsung a year to really pimp out the Smart Hub and make it more usable - we are still beta testers for this new smart TV stuff - hasnt become the norm yet.