Depends what are you using the camera for. If for hobby, the depend if you have the $$ and willing to spend.
D600 is Full Frame Sensor, obviously there will be a lot of difference overall. Again, depends what are you using the camera for? what do you shoot? do you need it? Got $$? Willing to spend?
Upgrading to FX you might want to get an FX lens to fully utilize the focal length and MP (FX lens means there's more $$ involved aside from the body itself); of course, you can still use the DX mode and make do, all depends on you.

One more thing, put your eye to the viewfinder on a FX body, you will see something different already.

So, who bought D600 ? No one ?

Mind to share how much u get it ?

So your current lens?
Did you change or?

any pictures to show ..

ferry!!!!

Not sure got anyone own or uses that before, so very hard to get answer.

Nowadays, you can google and find many reviews, even better, go YouTube, you can find video reviews.
I think DigitalRevTV did review this PZD version before.

seems like the dust in d600 sensor is a common issue
my friend's unit has 2 big spot.

Mirror easier la. Use blower to blow only ma.

Better have a powerful blower

Mine, can't even get it out while I'm using the biggest giotto

Congratulations on your new purchase! As for the weight? Just get used to it, 24-70 weight is nothing.

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Added on October 13, 2012, 7:31 am

More gym or training... 

or

Battery grip. More grip = less stress

Sell it and buy 2 primes, seriously u never test the lens before buying? 

get a grip and a comfortable strap.

wait till you hold 70-200 2.8 or 80-200 2.8

get a Q-strap, best strap i found so far