Well worth it.
Here is why:
First it adds a couple new things just like every version. Except that this years version adds some things that make the game more realistic therefore making it a better football simulator. Some of those additions are new tackle animations, and other new general game play animations.
Second it builds on the online dynasty mode sorry to say I can't elaborate on it because I haven't played it much yet but I can say that there are new additions, i just don't know what they are yet. The high school legend mode isn't really changed but Kirk Herbstreit and Erin Andrews follow your progress through high school all the way to college graduation day. All the while commentating on all your biggest plays, highlights, and performances at the end of each week.
The first main selling point of this game is the new season showdown mode. Now before you say who cares, listen to what it brings to the game. Its a system that counts skill points that you get from scoring touchdowns and tackling etc. It also keeps track of sportsmanship and strategy, which is the main thing that can change the way you play. This is because it causes you to think before you run up the score or go for it on fourth down in the first quarter of the game otherwise you lose points. You can gain sportsmanship points from punting the ball on fourth down or kicking field goals, and kneeling the ball to run out the clock and seal the game. Strategy allows you to set up plays after running plays similar to them. Then once its setup it will increase your chance of fooling the defense and making a big play whether it be a run or pass play. All these categories level up as well as you progress in skill.
Also they allow you to now change the way your offense and defense plays before you choose a play. You can set your team to play aggressive, which gives you a chance of making big plays on offense, and on defense it makes interceptions and fumbles more frequent. You can also make it balanced which just sets everything to default and then conservative which is pretty self explanatory and i don't feel the need to explain. Oh and by the way changing these around can be very rewarding because if successful you get a lot of strategy points.
When the real college football season starts you choose your favorite team and your points get recorded from then on after each game of the season is played. Keep in mind that since this is following the real life season you only play one game a week. So if by the end of the real season you are in the top 100 players rankings based on skill points you will be entered into a single elimination tournament. With the chance to be crowned this years showdown champion. This new addition will almost certainly be carried over to the next version of this game.(this is only accessible to people with online capabilites.)
Lastly but certainly not least and the sole reason to buy this years college football is easportsworld.com's teambuilder!!! It is the the deepest create a team mode ever. You can choose whatever you want for a logo and i seriously mean absolutely whatever you want! There is also a huge selection of jersey types. Each part of your jersey can be edited from head to toe. The only thing that isn't in this team-builder is the ability to create your own stadium, you must select from the list of 100 or so team stadiums. However you can edit the field.
If that new addition alone doesn't compel you to buy this latest version of NCAA Football 10 then by all means don't buy it.
That's all i can say.