I'm sure i'm risking having my throat slit by an angry mob of "true" Deus Ex fans... but i really thought 2 was quite entertaining. .
The only worrisome part of Deus Ex 3, to me, is the Spector-less design team.
As perhaps one of the biggest Deus Ex fans around (top of my list of favorites), I am highly likely to be mailing someone both my ears.
System Shock 2 was made by a completely different team than 1, and it ended up being even better.