I have seen all the nominated films - must be the first time in my life - and these are my thoughts.

Best films:

Whiplash - TIG
The Grand Budapest Hotel
Birdman
Selma - American Sniper
Boyhood
The Theory of Everything

I think Whiplash and TIG are both extraordinary movies which bring together all elements needed for a memorable film: strong script, excellent direction, outstanding performances, score, editing and powerful, moving story. May be Whiplash has even an edge on TIG, although the latter tells a more "important" tale.
The Grand Budapest Hotel is a delicious film and flawless artistically, but it somehow lack the emotional element for me.
Birdman is funny, engaging, has excellent performances and direction, but the script is not really original, the dialogue full of cliched bits and it has some structural problems, as well: Edward Norton's character is just not going anywhere, which is a shame, other characters are only sketched and in the end it's only about Keaton and his not-so-original aging man crisis.
Selma and American Sniper are very traditional movies with good performances, but lot of cliches and predictable scenes. Curiously, AS is far better in the first half of the movie, Selma just opposite.
Boyhood's pseudo-documentary formula doesn't work for me, they were very brave to be 12 years a slave of the film, but it didn't result in compelling story, good structure, interesting performances or memorable direction IMO.
And TTOE is a film that should never been even considered for a nomination, while so many better movies have been skipped.
The irony is that neither TIG nor - even more - Whiplash are considered serious favourites.

Best actor - I am rooting for Benedict because his performance was the best, hands down. Keaton was excellent, as well, even if not nearly as subtle and profound. Bradley Cooper was pretty good in AS, but he couldn't fight against the script. Carell shouldn't be in leading actor category. And Redmayne - he did a great job imitating Hawking's physical degrade, but little else, IMO. He is capable of far more, but the script was just too weak and even potentialy intense moments were reduced to some cheap telenovela emotionality. Still, he seems to be a frontrunner, which just shows that Oscars are not necessarily about quality.

I personally don't think TIG will win much. I WANT it to win much, but I don't think it will. Both Morten Tyldum and Ben are too new in Hollywood, and they are up against some giants and seniors this year. But being nominated is a great sign of the high quality of the cast and crew for this movie.

I think best movie will be Birdman or Boyhood and best actor might be Eddie Redmayne. Those are my guesses.

The only nominee I saw for Best supporting actor was Edward Norton and I loved his performance in Birdman.  I think he was better in this than Keaton really. 

I have been interested in Norton a long time.  Why?  Because I think Roger Ebert said it best - "The actor Edward Norton has never agreed to appear in a film he didn't believe he had reason to respect."  He has passion, dedication to his craft and does really interesting work. 

I saw 2 of the five nominees for best supporting actress Keira Knightly and Emma Stone.  Truly torn about this one as both were really wonderful in the respective roles.  The second time I watched TIG I had a chance to really focus on KK's performance and came away with a deeper respect of what she brought to the table with that part.  It was a very remarkably nuanced role and KK pulled it off in spades! 

But ES in Birdman was... luminescent.  No other word for it.  She was the heart and soul of that whole movie and she shouldered that burden wonderfully I thought.  She wasn't an easily likeable character but WOW! I felt shaken at the end of Birdman because of her. 

For best actress I saw two performances - Rosamund Pike and Felicity Jones.  I didn't really like FJ's take on her role.  Thought she was too controlled in her performance and thus it was bland to me, lacking in all passion.  I like subdued characters but not if I don't feel anything underneath the repression and for me there was nothing behind her performance.  It was all so flat. 

RP in Gone Girl... she was  all right when I was watching her, but nothing stuck afterwards.  I can't say she impressed me in a big way but at least she was entertaining when I was in the movie house.  So, if I had to choose between the two actresses I saw it would go almost by default to RP. 

For best actor - I saw 4 out of the 5  nominees.  The only one I missed was Steve Carell in Foxcatcher.
Even if I wasn't a fan of BC, just judging on the performances, I would still pick him for best actor.  Dan isn't "benedicted" like I am (he just looks at him as an actor, like he does all the rest of the actors) and he thought the same when we talked about it.  I have already written reams on his inhabiting of the role of Alan Turing and how wonderful the performance was, so suffice to say I loved what he did in the movie.

ER in TToE was fine in a physical sense depicting Hawking, but I didn't get any sense that he made me see who Hawking really was beyond the physical sense at all.  His performance didn't make me feel for Hawking.  It was too dry. 

Keaton was very fine in Birdman.  It was a difficult role to do for sure.  It really spread across a wide range and he covered all the bases. Sometimes I think there was a bit too much histrionics on view, but if Ben doesn't win then I hope MK does. 

Bradley Cooper, like the movie he starred in, doesn't deserve to be a nominee IMO.  Could have been the poor script but I have to admit, I have seen him in a number of roles now and I still don't like him as an actor at all.  Frankly, I don't think he has the chops.  Didn't like him at all in Silver Linings Playbook  - he stuck out like a wooden sore thumb in the cast as far as I am concerned.  And I saw him again in American Hustle (a movie that I actually liked a lot despite B.Coop) and thought he was even worse in that one.  American Sniper was even a bigger step down from American Hustle - never thought that was possible, but there you go... 

-Val