Brilliant Film. I've watched it multiple times and each time it feels new and refreshing. Suriya is Fantabulous in the film, he is indeed a very Versatile Actor as he differentiates each of the 3 roles with such ease. Samantha has portrayed her role with grace and beauty. Saranya ma'am is superb in the all the emotional sequences. Nithya Menon has done a decent job in her role. The Time travel concept of 24 has surprisingly been handled exceptionally well. AR Rahman BGM and Songs are just Amazing, one of his best pieces. Vikram Kumar's direction is crisp and very interesting and entertaining.
The only minor drawbacks include the abruptness of certain songs in the film which leads slowing down the pace of the film; the exclusion of a small backstory explaining the reason for Athreya's hatred for Sethuraman; and the lack of exploration into Samantha's character's personal life.
Barring all this, 24 is indeed a cult film which deserved better in the Tamil Nadu Box Office gross.