I'm a big Sly fan, and fell in love with the original. However, I found it to be really short. I really want to get this because of the $40 price tage and since it comes with the vita version, but I fear I will beat it within a week.
It took me about 12 hours to beat the story I think, but there are lots of collectables and goodies to hunt down. Personally, I think this is the best of the Sly games gameplay, humor/cuteness, fun, and graphics. The story is still solid but you'll probably like the past stories better. Overall, its definitely worth your money if you're into Sly and it put money towards a genre of games that deserves more than it has.