The only way to see Raavanan is to look at it from the context of Ramayanam. Not that Mani ever lets forget you and in not so subtle ways let me add. Vikram screams pathu thalai often, karthik jumps around for no reason save this reminder deal and so on. But even then when the subversion happens between the good and bad, it just seems a literal transfer - not a blurring of line between evil and good as the promotions claimed rather a total role reversal. Especially we have only see the gangster/mafia/anti hero in the good light like .. wait at least a few times(across various languages) EVERY year since God father released(i,e *35!), this role reversal doesn't register in one's head.
In the versions of Ramayan I have heard, Raavan was always described a good ruler, a great devotee - his only crime falling for another man's wife and keeping her captive for that reason. With that if you transfer the evil act to other side, what could be the point of debate? Are we supposed to act surprised that this police officer - he is supposed to Ram and all but nothing gets defined in that way except for couple of dialogues proclaiming him so and character being called Dev isnt really on the good side?
And what was the 10 head deal? - he doesnt seem to be confusing at all, he seems the straightforward antihero - the typical Good guy on the wrong side of the law.
When Sachu Kichu was really small, Solomon Papaiah and team will some time take a break from their mamiyar/marmagala, nathanar/maithanara type patti mandrams and have Ram/Raavan or Sita's agni pareeksha debate which used to be lot lot more intense than this film. For any one who has seen this sort of patti mandram would know what an insult this is.
If you take away the ramayan angle, there isnt anything left at all. At the climax, there was a possibility of starting the film through questions in Ragini's mind but that door is just shut abruptly with focus just on Veera so you are confused as to what the deal at all was.
So we are left with Vikram's nuanced performance carefully averting the over the top tag even though he stands dangerously on the edge, very good looking ash but whose age just shows through the climax scenes esp. next to Prithviraj and decently looking prithvi(he hasnt looked this good in any of his films) and overall great performances - the expected deal in Mani's movies. But there are lot of other expectations that Mani has never ever failed on and falters for the very first time. And here I went expecting something better than Kannathil Muthamittal and Iruvar so that he can wash off the memories of Guru and Yuva, now I will just watch Guru.