Eeehh, I guess. It never had the 'sandbox' effect I associate with that term though. Stalker did, Hidden and Dangerous 2 did. Crysis? You just shoot people and it looks pretty, sure you can shoot them in a different order, and it looks nice but there is not much more to it..
When you actually take a step back and look at the term 'sandbox' it is actually quite dumbed down in Crysis.
Maybe I'm wrong, it has been a few years since it came out but I remember completing it back then and just moved on. It didnt shift the earth in regards to something earth shattering for the PC.