Just finished story so I'm going to give full impressions. Full on spoilers and a massive post ahead.
Overall, I'm mixed, but mostly pleased. I was extremely hyped for the story expansion, but for some reason I feel that it didn't deliver somehow, especially towards the end. First off, I'm very impressed with Capcom and their attention to detail when it came to the lore of the previous games (especially SF3) and the amount of NPC fights. Good job on that regard. My complaints and feelings towards some things, however, are my own and they don't normally follow other people's opinions, so be warned that I'm probably going to hate what you loved and vice versa. Anyway, let's move on.
First off, I felt like nearly everyone played a decent role in this. The only people I think I got shafted were Birdie, Mika, Laura (although they had some cool scenes) and Alex. If you know me, then you'll be aware that I'm very fond of Alex. I was very disappointed with how they dealt with him in this. For someone who is meant to be the protagonist and the main adversary of the next chronological game's (SF3) boss, Alex did absolutely fuck all in this. All I remember him doing was being in a wrestling ring and then giving Dhalsim his statue thing. Very disappointing and somewhat continues the trend of Alex being shafted to secondary roles post-SF3.
On the topic of roles, Necalli was probably the biggest disappointment in all of this, next to Alex. For being pumped up so much prior to the cinematic story releasing, he did nothing. I still don't know what his deal was or what his purpose even being there was. When he turned up after being gone for like two acts I had completely forgotten he was even in the game. There was no explanation for his V-Trigger ability, he wasn't related to the Illuminati and he had nothing to do with the Satsui no Hado. All in all, a complete waste imo.
I was pretty shocked to realise half way through this that Rashid is meant to be the new protagonist of SFV (just like how Alex was for 3 and Abel for 4). Prior to the cinematic story mode (CSM) I wasn't very keen on Rashid due to his personality shown in the character stories, and that continued into story mode. He improved a little towards the end with his fight with F.A.N.G, but I think this is the first SF protagonist I don't like.
Nash's role was a big shock for me, seeing as I considered Nash the protagonist for this game prior to CSM, his role was very minimal compared to what I expected it to be. There seemed to be a lot of build up around Nash and his resurrection, but it turns out that Nash wasn't even resurrected. Judging by the comments by Urien and his story mode, Nash appears to be Eleven's, the predecessor to Twelve, body reformed to appear like Nash. (I could be wrong on this, so if anyone could clarify that would be great). This was a great swerve and one I wasn't expecting, but at the expense of Nash in SFV being kinda ruined for me in a weird way I'm not sure if it was necessary. Hopefully with more clarification I might change in this, but yeah Nash kinda fell by the way-side, like a lot of characters.
I'm not the biggest fan of the dolls, so they're appearances and NPC fights did nothing for me. I'm glad they're free of Bison's control. Hopefully it means it's the end for them in SF. I'm not really fond of 12 Cammy clones and rather they didn't appear again. I'm expecting Decapre eventually though as DLC for SFV.
I feel like they're could have been more cameos though. Apart from one or two that caught me by surprise (Mel was one), all the NPC cameos were very safe and predicable given the characters we knew were going to be in the game. The cameos that were there were great though. Sean's was great and his interaction with Laura was one of the better parts of the story. I'm also a lot more fond of his design, although I'd prefer the one in the character bios. Like I said earlier, Dolls did nothing for me. Abel was a great surprise and I didn't expect him to be in it as much as he was. Gill was great. Really happy the he was in it, even for a second.
Urien and Juri feel great to play. Even though they're not finished, I can tell I'm going to like them. Their roles in the story were good, but I feel like Urien should have been in it a bit more. Juri was in the game a lot more than I thought she was going to be.
I really, really hope Bison and Shadaloo are done for good. I'm sick of Shadaloo and I really want either Gill to be the boss in SF6 or someone new. Bison and Shadaloo are stale now. They've played their part more than enough and I can't honestly see what more they can do. If Bison is back in SF6 then I'm going to pretty pissed off. He should be done now. No need to beat a dead horse. Bison (and F.A.N.G hopefully) being killed at the end as well as Vega and Balrog seemingly ditching and running away is a good sign, that Shadaloo is done. It's time to move on.
The epilogue was very flat for me. I'm not sure if Capcom have left things open for another CSM with Season 2. One one hand, several characters (mainly those who actually are in SF3) kind of feel like they're journey to SF3 is expalained now, but on the other it feels like several characters (mainly those not in SF3) are not given a good enough explanation for their future absence. They don't explain why Cammy, Guile, Juri etc., people who you'd think could have been played a role in SF3's story, aren't there or even mentioned. It's up to this game to explain those absences and I feel that they didn't. That's a major let-down for me, as Capcom have been saying that this ties the gap between SF4 and SF3, and those absences are a major question still left unanswered and leaves that gap with a lot of holes. If a second CSM is done, then those absences can be explained. However, I feel that this is the only CSM for now. As of this moment, I feel this is a very weak bridge between the two games.
I liked quite a lot of what was on show here. The interactions between some characters was cool and I enjoyed seeing previous relationships develop further. I'd probably give the story an 8/10. It wasn't terrible by any means, and Capcom did a pretty good job overall. I enjoyed playing the CSM and I'll probably play it again. There were some minor problems that bugged a lore nerd like me, but it's easy to ignore that and just enjoy this story for what it is. The only thing I would have changed is have more links to SF3, but that can easily be rectified by future DLC characters. For Season 2 DLC, my predictions would probably be; Abel, C.Viper, Sakura, Oro, Decapre, Sagat, Azam and Ed.