You can use the keys to switch it back on straight away though, or switch to 'speed', run away, hit 'armour', recharge the suit, hit 'stealth' again.... god I love this game
I just spent about an hour replaying the first big set-peice with the huts on the beach looking down from the hilltop.
Its amazing the number of different ways you can go about the same attack, and I'm also impressed with the non-predicatbility of the bad-guys. And doing the Predator thing where you mow down the trees with the mounted machine gun on the jeep is brilliant.