Batman v Superman is a spectacular movie that was spoiled by the trailers, and also tried to cram in too many storylines in its 150-minute runtime. The result was the ultimate fan-service with a predictable plot for hardcore fans of DC, and a confusing experience for casual fans of comic book movies.
I will try to keep the review spoiler free; that is I would not discuss anything that was not already shown in the trailers, except for one short paragraph near the end of the review that will be marked with the *SPOILER* tag.
Okay, let's get down to the nitty-gritties: Zack Snyder is a master of spectacle. I never thought I would see certain panels from comic book pages on the big screen, but Snyder managed to create another faithful adaptation (as he had done in Watchmen and 300). However, the script was not on par with the visuals. There were too many storylines and plot-holes, and the screenwriters (Chris Terrio and David S. Goyer) overwhelmed the audience with the number of characters introduced here (who are supposed to appear in future movies).
I consider myself a hardcore DC comics fan. Seeing the Trinity on the screen (although it was already shown in the trailers) gave me goosebumps. Also certain visual nods and easter eggs from influential stories from DC canon made my heart skip a beat a few times. But after a split second, I realized I knew what was going to happen next... These verbatim translations of plots from some famous storylines and also the plot-points that were already spoiled in the trailers made the movie predictable to me.
But for casual fans, those revelations, easter eggs, and climactic moments had no or little significance, and probably felt unearned; seeing Wonder Woman in her armour for the first time, and also the way the fight between the titular characters ended are examples of this.
Some fans also criticized the darker portrayal of Batman and Superman. We had already seen Superman kill General Zod in Man of Steel (2013), and in this movie, we see a more violent version of Batman. I fully realize that some of the things that these characters do is in violation of their respective moral codes in the comics, but I found this creative licence to be as valid as any other interpretation of these modern mythologies. While on this, I was already a fan of Henry Cavill's Superman, and this film made me a fan of Ben Affleck too. I remember back in the day when he was cast as Daredevil in 2003, people were saying that DC missed out, but when Batfleck was announced at the SanDiego Comic Con in 2013, same people freaked out... I'm really happy that Snyder and Affleck proved them wrong. Affleck was perhaps the best Bruce Wayne that we have seen on the screen (a close second might be George Clooney in the universally-hated Batman and Robin 1997); for his Batman, the credit also goes to Snyder for showing us the most brutal and efficient Batman. Of course the Batman interpretation was heavily influenced by Rocksteady's Arkham universe, and the costume by Frank Miller's Dark Knight Returns. I just hope they redesign the cowl for the next movie and make the ears a little longer, and also show a little more of Batman's jawline...
*SPOILER* Another major issue that people have with the film is about how Batman and Superman stop their fight and become allies: When Batman is about to pierce Superman's heart with a Kryptonite spear, Superman says "save Martha"; Batman suddenly stops and becomes friends with Superman because their moms have the same name. This may sound silly, but I'd like to be the devil's advocate and put myself in Bruce Wayne's shoes for a second; witnessing parents' death might be one of the most traumatic experiences in a person's life. Batman hearing his father's last words would trigger a lot of emotions and perhaps paralyze him for a second... Psychoanalysis aside, this a comic book movie for god's sake. People had no problem when Tony Stark's PTSD was triggered every time someone said New York in Iron Man 3 (2013)... Okay, while we are spoiling things here, I'd like to give shoutouts to Darkseid's Parademons in Batman's dream sequence, which was also a vision from the future brought by Flash (as he had done in Final Crisis and Flashpoint storylines), and also to panels taken from Dark Knight Returns and Death of Superman (Batman on top of the crane holding a rifle, Batman escaping from Doomsday using his grappling gun and thunder striking in the background, and also a torn piece of cloth on a pole right before Superman delivers the final blow to Doomsday). *SPOILER*
To wrap up, I just think if Lex Luthor was the only villain of the film (and we didn't have the last act in which they all fight Doomsday), perhaps the story would have been more coherent and less confusing for casual fans. But regardless, the movie has sold pretty well ($800 million at the boxoffice as of this writing)... I had a great time watching this movie: I had goosebumps, my heart skipped a couple of beats, do not remember blinking too many times, and I didn't look at my watch even once. But at the same time, I acknowledge the shortcomings of the movie and understand why some people may not like it as much as I did. Seems Marvel is doing a better job at pleasing the casual fans... Overall, I give this movie 9.5/10.