What will be your first reaction after listening to a Rahman sir song ?? You feel a major let down, You feel like why Rahman is doing all these kinds of stuff. You feel like, why is he not composing music like Roja, Dilse, Lagaan. ( The matter of fact is, There are already classic hits like Roja, Laagan, There's no point in giving us something similar to those albums.)
The second time you listen to a song, u slowly start humming the tune. Next time, few lyrics to it. Allow the music to run in loop, non stop. Now each and every time you find at least something new, minutest layer or an instrument playing in the background. You start wondering how many layers are added to lead. Now his music starts growing on you, exponentially. You start feeling that, how come this man keeps us flabbergasted with his music. Every single time.
One striking feature that differentiates a Rahman song or any other song is layering. Layering is a concept where different instruments play at different times. Take for example, songs like Anbae sugama of Parthalae paravasam. How brilliantly he uses violin and keyboard. Blissful. or take Chitti Dance Sequence in Endhiran. Every layer in the track sounds different. Each time you listen, there would be a small instrument in background along with the vocals. Also contributing to the fact is the quality of speakers or headphones you use. Not to say, the original cd music is always top class as compared to the downloaded pirated ones.(Be a music lover, not a music pirate)
Much of these credit should definitely be given to Late shri H.Sridhar, who has been a pillar of strength for Rahman sir. It's very difficult for anyone to fill in the shoes of Sridhar, which is evident from the sound quality of recent albums(with due credit to the albums). Post Oscar , thalaivar seems to be on an experimentation mode, with getting new genres, new voices, new instruments. If it was Blues in Vinnaithaandi Varuvaaya, funky African instruments in Raavan, Mass in Komram Puli, Major techno mode for Endhiran.(Per Se, treating each film on its own merit.)
I think the fans, as a whole will keep supporting his nouvelle experimentations in music, allow Rahman sir to explore new kinds of music and collaborate with new artists. For sure, we will like his experiments.