Depends what you are used to.
If you only ever used, say the Sigma 70-300 DG, you'll love it.
If you've used a Nikkor 300mm f/4 of any flavour, you'll won't be so keen.
Its a decent enough lens, but for Nikon shooters you've got to consider a 300mm f/4 first.
having tried the three lenses you mention I would put them in the following order
1. 300mm AF-S
2. Sigma 100-300 F4
3. Nikon 300mm AF
the af-s F4 is stunning but as you had only mentioned the 100-300 thats all I commented on
Think that may be beyond my reach atm...
I'm no Nikkor lens badge freak, but in this instance, the Nikon 300's are SOOO much better than the 100-300 - if you really need a very good 300mm get saving.
I'd personally put the 300mm AF-D ahead of the Sigma 100-300 as well. Its wide open sharpness where you see the difference.
will it work on full frame?