Pally Tank: Crit Immunity and Holy Shield?

I got a question -- seeing the cata info after the NDA has been lifted. I am worried about Crit Immunity for Paladins. The way the text seems to read is that Crit Immunity is only for the span Holy Shield is active.

Q u o t e:
Reduces the chance you'll be critically hit by melee attacks by 6%, increases chance to block by 30%, and deals 79 Holy damage for each attack blocked while active. Lasts 10 sec. Each block expends a charge. 8 charges.

Can anyone shed some light into this?