Snape's Character Progression

[Thats my little secret]

Things I've noticed...

SS/PS~Physically has more of an emotional response. When he was 
listening to Hermione's troll story, you could tell by that one look 
(made me LOL so hard BTW) he knew she was lying andthat he was 
disappointed in Hermione, some who's obviously smart enough to know 
better, for doing such a dreadful thing...

CoS~He's a bit more subdued in his expressions, subtly showing his 
abilities in legilimancy (mind reading). An easy example, when the 
trio are found with Mrs. Norris, he offers his opinion on what 
occured because of his ability to sort truths from falsehoods, one of 
which almost came from Hermione but was picked up by Harry.

PoA~Not featured as much as the previous film, perhaps because of the 
character's backstory multitasking Death Eater meetings, teaching, 
the Dementors constant survey of the school grounds, and of course 
Sirius Black's escape, who he hopes to catch himself, part of a past 
vengeance. When we do see him, he seems far more vulnerable here, 
stumbling, facing his fear of Lupin's alter ego, brimming with 
obvious anger and overprotectiveness of even Harry himself.

Then there are moments where he's in the scene, but hardly focused on 
until camera leads up to the principals. For example in the hallway 
(SS/PS), he spins around upon hearing conversation between the trio 
(Ron, Hermione, Harry).  

I still haven't read GoF (shame I me, I know) but I'm looking forward 
to any subtle differences Rickman puts into any future performance, 
and I certainly hope he sticks with the other adaptations because he 
brings a certain substance and dimensionality that few actors can do 
to an otherwise tragic character.

That's just my personal observation though...any other thoughts?