Sandeep, have you experienced a big performance increase by rooting your G2?
I have to admit I'm worried about voiding a warranty on a brand new phone.
Cant really answer that one properly because I haven't overclocked or done anything to the phone just yet - I'm happy with its current speed and performance. I'd rather have better battery life at this point so what i've done is i've underclocked the CPU speed for when the screen is off, and when the battery is <20% (which suits me fine).
I did run a Quadrant test the other day and it blows the competition away.
With the custom ROM, i get the custom features too. I decided to keep the ADW Launcher instead of pushing the default G2 one back... also i managed to use the ADW settings to alter the resolution so i have more space for icons and widgets on the homescreens.
One thing i cant stand is the 3.5mm audio jack being at the top. I've got around this problem by allowing my phone to be used upside down (180°), but i still have to put my phone back in the pouch the way I don't like it to be... minor issue anyway, but just a bit irritating.