Well, Crysis usually is about stealthing but in C2 its almost impossible to stealth proper cause u get detected as soon as your head just pops out a bit 200 m away and the enemy doesnt even have to point at u. Also when u stealtk kill someone u become visible shortly but most of the time an enemy notice it even when at a totally different location.
Yes, u can hide and wait till the enemie loses interrest but that just feels unreal.
FC3 has a very good stealth feature and i hope Crytec look at their old franchise and be inspired a bit by it.

In FC3 stealthing works more than well and also feels realistic as u can hide the killed enemies.

In C3 thete should at least be the possibility to complete a section without getting detected. Its not a thing of difficulty but of logic

Far Cry 1,2,3 is mostly Ubisoft.