Sly Cooper: Thieves In Time may have been released to a mixed reception. However, that should not deter you from trying the game out yourselves.
Just so that you can do that, the developers of the game, Sanzuru Games, have dated the demos of the game.
The demo of the game will be available in the US and UK on the PSN on the 20th of February. Keep in mind that the game has already been released in North America on the 5th of February, and it will be released in Europe on the 29th of March.
Furthermore, Sly Cooper: Thieves in Time features cross play function between the PS3 and PS Vita. This feature allows you to download the game on PS Vita freely, if you have already purchased it on the PS3.