I have been thinking of getting this game and was wondering is it worth it? How much better is it than GT5?
PS: If I do get this game right now, are there any ways to get lots of money fast? Like millions at the start because I do not want to grind I just want to drive a bunch of nice cars.
Depends on what you want out of it. It's similar enough to GT5 that asking if it's better or worse is really a moot point. The physics are better especially if you have a wheel. The new tracks are fantastic, some of the new cars are very good. If you liked the Career Mode in GT5 it's not much different except the races are shorter and there's no endurance racing. The AI are not challenging at all and no improvement has been made there, you might argue the rubber banding is even worse. Online is slightly improved but still no way to search for what you want other than a few basic sort parameters. If you want a certain PP or Tire Compound you can't use it as a search parameter.
Course Maker and BSpec are not in the game as of yet. Sounds are the same except for a couple of the Senna cars and the RedBulls.
I'd say if you liked GT5, you'll like GT6. If you were looking for dramatic improvements in many areas, you'll probably be disappointed. If you like hotlapping and new cars and tracks, it's worth it for that alone.
There was a money glitch early on, and anyone that capitalized on it, like me, has a garage full of cars, $50 Mill in the bank, and barely had to touch the offline career. I thought I'd give it a shot but after a couple of hours I just wanted to rip my face off it was that boring. That money glitch is no longer available

but there is a RedBull thing you can grind to make money fairly quickly, but it'll take you an evening I think to earn enough for one of the $20Mill cars. I don't grind though, so I may be off on that estimate.