Well it depends on what you are interested in. The standard 1600x900 resolution screen is a TN panel while the 1920x1080 screen is an H-IPS or S-IPS panel. Huge difference in the cost of manufacturing which is why it is a rather steep upgrade.
For watching movies on a relatively small screen, I would say the difference shouldn't be that great when watching a 1080p on either a 1080p or 900p screen. Shrinking down a high resolution movie to fit a smaller resolution screen is not nearly as bad as stretching a smaller resolution movie to fit a larger resolution screen.
If you are doing photo editing or anything that requires color accuracy, then the $300 for a higher resolution IPS panel would be worth it. If you are just a "normal user", then perhaps sticking with the standard 1600x900 resolution would be the less expensive choice.
If it were me I would be somewhat conflicted. I definitely prefer an IPS panel over a TN panel any day of the week and I would perfer a 1920x1080 resolution screen on a 15.6" laptop. But the $300 upgrade option, just barely high enough to make myself wonder about spending that extra cash. I might just have to down an entire bottle of scotch just to convince myself that the upgrade is worth the $$$.