Some people have stated that they find themselves rather weak and the suit powers lacking in Crysis. I think there are other factors then just the limitations of the suit powers that make you feel relatively underpowered. For example, one biggy I always think of is the fact that the Koreans are insanely armored. They don't wear nanosuits, but their armor vests are crazy good at stopping bullets. Even landing a headshot doesn't work unless you shoot their exposed face, their damn helmet will deflect a bullet. Really frustrating sometimes. I think if they had lowered the toughness of the Korean soldiers, you would feel a lot more powerful. Cause sure, cloak would still only last 5 seconds, but it wouldn't matter if you could drop a Korean in one burst to the torso.
Having to go for headshots was tolerable from a gameplay standpoint, sure. But as far as suspension of disbelief... I dunno, it was strange. Here I'm a Delta Force soldier equipped with the latest and greatest R&D armor, with friggin nanites and all... giving me rather outlandish powers and protection in this near-future setting... yet I'm still using guns that seem pretty weak and old-fashioned? Well okay, not the gauss rifle, that was awesome... but the regular assault rifle you're given is pretty ineffective against these Koreans. It's this strange disconnect. On one hand your armor is amazing and sci-fi, but you use a gun that seems to be no more powerful then an M-16. Oh wait, it can hold 10 more rounds in the magazine. Big whoop.
Actually, around the middle of the game, I think I threw away the assault rifle entirely and just kept a loadout of the shotgun and a sniper rifle. You get the best of both worlds... long range sniper kills and then close range one shot kills with cloak.
I had the same problem with Halo. You're given this insanely powerful power armor, with force shielding and everything... and yet you're running around with an assault rifle that seems about the same as a standard NATO 5.56mm rifle... sniping with a sniper rifle that doesn't seem all that different from a Barret .50 cal sniper rifle... it's like "What gives, guys?"