In particular, I wanted to observe Ehsaan's work, having been fascinated by some of his strumming I've seen on TV during interviews. He was very good, in particular some of the spontaneous riffs. Shankar looks after the stage elan bit for the group. One could see the difference in how he could mould the audience mood, especially in contrast to some of the younger singers accompanying the trio. BTW, these were Raman Mahadevan ("kholo kholo darwaaze" - Taare Zameen Par), Akruti Kakkar (the title song in Johnny Gaddar), and a third lady about whom I only remember that it was her birthday that day. It was pretty good to see the younger performers being promoted, including some very young musicians, including a keyboardist and a percussionist.
S-E-L played many of their hit songs, ranging from Taare Zameen Par to Jhoom Barabar Jhoom to Kyun! Ho Gaya Naa. I was hoping for some elements from their jazz backgrounds, and wasn't disappointed when they improvised (or so it seemed!) jazz version of some of the interludes in the song "Dil Chahta Hai". That, and Shankar's hit song from Aga Bai Arrecha, were the highlights of the night for me.
In short, if you get a chance to hear them live, go for it.
George has a post with some more links to Ehsaan Noorani on the web.