You need to have a lot of money to be comfortable in India.
You also need endless patience and tolerance.
I went for a few weeks and was worn down by the time I left.
I can only imagine what spending a year or two would be like for a foreigner.
Don't get me wrong, there was lots to see and do but I was constantly seen as a target for a rip-off.
There are some nice ppruners there though - Bombay Duck for one, who showed me around his city for two days and made me feel very welcome.