I do not have a AMC. I didn't go for it as I had already covered 20000 kms at that time. It costs about around 40k for 4 years/40000kms. It covers everything except value added services like interior cleaning, polishing, etc and accident repairs.
You should check with your SA to get complete detail of the AMC and decide before your first oil change.
BTW, the service manager, one Mr. Suresh (I think), from Prerana motors (kudlu gate - hosur road) is now the SM in KHT. Deal with him carefully. He keeps insisting for each repair that "Sir, it is now 99% better" Even when the Tatamotors' representative agrees that the problem has not been solved.