The movie

Overall

First of all, even if it doesn't show in some parts of this text, I really enjoyed the movie!  It was good to see Hogwarts and all the characters alive again!  
However, I was very disappointed from the start because here is how the whole movie unfolded: almost everywhere Snape was supposed to do something important or show how cunning and intelligent he is, someone else did his job!  Not all of his job, but always a small bit of it! What's their problem?  No, really, this was so stupid!  Rickman could have done such a great job at it!  Don't be deceived though, the duel scene was still outstanding and all. Every part involving Alan Rickman was great!!  It's just that you have to see the movie and not suppose that Snape will do as he did in the book. I say this because I don't want other people to be disappointed too much when they actually see the movie!  Just knowing this will make you feel better and less expectative! But you have to see Snape again, that's for sure!!  His parts were good!

One other thing I enjoyed about the movie: they did cut Snape's parts, but they've put in a lot about the Malfoys.  These two seem more tri-dimensional now!  So, when you watch the movie, look out for the Malfoys.  They've been very well cut out for the public. Not so much in talking but a lot in facial expressions, mannerism and actions!

Scene by scene

First scene - Discovering Potter and Weasley

I don't like that scene because it's different!  The only thing I love from it is the facial expressions Rickman used to make Snape more tangible to the audience. Look at that when you see the movie, you won't be deceived! But even so, it was not as glorious as in the book!  Maybe Rickman could be more expressive.

Mrs. Norris

Here, Snape's part has not been altered so much! Wow! This is what was in the book: Potter and his friends may have simply been in the wrong place at the wrong time," he said, a slight sneer curling his mouth as though he doubted it. "But we do have a set of suspicious circumstances here. Why was he in the upstairs corridor at all? Why wasn't he at the Halloween feast?"  I'm not telling what was in the movie though!!

First Quidditch match

 The only thing I have to say about this is that we will see Snape!  

Swelling potion in Snape's classroom

Don't get your hopes too high with this part of the book! It would have been fun to see the stealing of potions ingredients, but I guess they didn't have time to do it!  It's a part of the movie they just had to simplify!  Sadly, we didn't get a chance to see Snape's classroom again!  It would have been cool to see the swelling potion!  That's a cool scene from every point of view, not only for Snape fans!

The duel

Here is the best Snape part of the movie of course! It's the longest and Snape finally does something!  I loved this scene of course!  

The duel between Lockhart and Snape is great!  We can feel the hate irradiating from Snape towards Lockhart just by the way he stands his ground, his cold attitude, not even flinching a bit, and his disinterested voice. All in all, Rickman was brilliant because he radiated Snape's personality!

Then happened something I really enjoyed and I want you all to look out for when you see the movie: Rickman tried to give himself an innocent look when he proposed "say Malfoy?"  I never expected that.  I thought that like in the book, Snape would be smiling instead of looking innocent.  But I love what Rickman did because it shows how Snape's trying to fool Lockhart! Snape just knows how to tackle Lockhart like a puppet on strings!  

So, Snape got at the end of the duelling table while Malfoy got on it.  You all saw that from the pictures. From that moment on, Snape's not doing a lot, but he surely is expressing!  First of all, when Draco and Potter take their battle stance, he looks at Harry, not at Malfoy.  I think he doesn't want to miss a single thing about Harry's butt being kicked up in the air!  

Then, like we saw in Trailer B, when Draco was sent flying in the air, Snape didn't try to catch him at all. I think Rickman just tried to look abashed. Yet, something that was absolutely not part of the book happened: I'm not telling you of course!  It's a small detail, but you'll see that it gives the relationship of Snape/Draco a cool Slytherin dimension.

Then, Serpensortia occurred of course as seen in the preview.  From that moment on, Snape is quite expressive which is nice to see!  

 Lockhart

 I truly enjoyed Lockhart because I know how stupid the man is!!  If you don't like Lockhart, try to imagine what Snape would be doing to him at the very moment you see him in the movie!  Then, you'll laugh for sure!  I just can't believe how Snape could actually bare to talk to him!  

"Her skeleton will lie in the Chamber forever"

Does he look like he has a plan or what!  

Believe it or not, they've given a bigger role to Snape compared to the other teachers in this scene!  Well, not that big, but still, he kept his place for once!!

I liked it because you saw that Snape was the main character and not Minerva even though she was there.  I think that if we could have read Snape's mind, we would have known that Snape thought Lockhart would flee in the face of danger. The only sad part of this scene, in both the movie and the book, is that we don't know what the other teachers will do.  I'm sure Snape will not leave this matter into the hands of Lockhart! He'd rather do so with Potter! So, I think it's a shame we know nothing of what he tried to do to solve the mystery.  I bet he tried to look for the entrance himself, somewhere in the dungeons since Slytherins seem to always have been there!  

The End

Alan Rickman's performance

Overall performance

Rickman was great, though it's hard to tell from the little screen-time he's had!  However, I think he did his best with that!  The first scene with him seems to me like he lacked the conviction, the joy of kicking Potter out and then the hate of not being able to do so. But due to all the changes that were made to this scene, I guess it's understandable! I couldn't see Snape fuming as I had expected he would, but Rickman did that with his face.  You could feel how Snape respects Dumbledore too. So, yes, Rickman did a great job with his facial expression!  Of course, each time we saw him, I was watching his every move.  I think Rickman understood that if he was not going to have any text to say, he was going to act it silently.  There were a lot of quick glances, glitters in the eyes, almost unperceivable movements with the head that gave Rickman a truly Snapish look.  I think that overall his performance as Snape could be described as such: cool, self-control, controlled sarcasm, expressionist, and cold.

Rumors about Rickman not wanting to participate in the other movies

Thanks to PIyanun, I've been informed that this was a rumor after all! I'm glad that's the only rumor I ever posted on my website, because that's the very reason why I hate them!  Here is what I learned on the Leaky Cauldron website:
The Facer has posted a retraction of their post from earlier this week, that Alan Rickman was considering stepping away from future HP movies because he hadn't had enough to do. Thanks to Amanda from HPfGU and a few posts to various Rickman sites, so TLC could get confirmation, we refrained from publicizing the original statement, but now that it's been shown to be a fraud someone tried to perpetrate on TheFacer, we're happy to say that it's not true. Reuters reports that Rickman is expected to be at the premiere in London early next month.

Rickman's touch!

A thing that really caught my eye was how 2 or 3 times Rickman gave Snape a somewhat "innocent-look".  What I mean is that, when he used sarcasm like Snape always does, at the same time he tried to look innocent.  One such occasion was when Snape proposed Lockhart that Malfoy duel against Potter.  It's like he tried to look stupid on purpose because he wanted Lockhart to agree to his plan!  I loved that little touch which I had not thought of when I read the book.