Cool title, but that's as good as 'ABCD' gets.
It's very much dance routine first, film second. They really do disregard any attempt at a proper premise, instead putting full focus on dance. In fairness, that's all the majority who choose to watch this will likely want. Still, they could've tried harder with the plot; which hits almost every cliché/trope imaginable.
This might've made for a fun/silly 90 minute production, but at 136 minutes it's a very long watch - it proper dragged, for me anyway. I was OK with events until the ending, which is awful from a story point of view. That's unfortunate, as it is actually set up well with a hearty event - the performance for which is nice, but it quickly loses any momentum that it created from it.
Prabhu Deva (Vishnu), while likeable, isn't lead-worthy in my opinion - he doesn't bring anything memorable or noteworthy to the role. Ganesh Acharya is alright to watch, he brings the amusement as Gopi. None of the dancers stand out, away from their dancing anyway.
A disappointment in many ways for me, though you may like this if you're in search of a film filled to the absolute brim with dance.