Yes it is worth $300, and no it isn't. The sporter job appears to be pretty well done, and the .30-06 is a versatile cartridge and it will be relatively easy to find ammunition for. However, the proof will be in how well the rifle shoots weather or not it was $300 well spent.
The Bushnell scope on top of it doesn't add any value to the rifle. Plus I can't tell from the pictures how well the stock and action fit together. I can't tell if the trigger has been replaced or is the old military two stage either.
What are your expectations of your first rifle? What kind of accuracy do you.expect? Are you willing to spend.more money on it if it doesn't perform to your standards? Plus you need to be honest about what you are going to use it for. If you are going to be mainly hunting it is hard to beat the .30-06, if just shooting at the range is your goal then there are better cartridge choices for that.
To me it is well worth the $300 for the rifle. However, I would also expect to put some money into it to get it shooting the way I want at the very least it would get a new scope right off the bat. That said I may have to do nothing to it as it could be a tack driving big game killing machine.