In the United States, most airports are very large and are full of bustling, busy adults that are hurrying to catch their flights on time. Are the airports in India more orderly? That would be a very nice change from what I'm used to. I don't particularly like airports too much; they tend to be an inconvenience because of how excessive everything is. There's crazy amounts of security too— while I understand why people like it, it's not that great to go through.
I think the major airports that deal with larger flights are pretty much the same as any other airport. Long lines at security will be the norm for most airports anywhere in the world, India included.
Airports are just like anywhere else. Some of the more busy ones like in Mumbai and Delhi will make you keep waiting for a long time. But the upside of these airports is that the experience is really great. The Mumbai airport after renovation is extremely beautiful, and the IGI airport in Delhi has been time and again named as one of the best airports in the World.
I had some very positive experiences with the airports in India. I think that I got lucky, though, because there were a lot of people around me that seemed to have more trouble. I guess that is really with any airport that you go to, though, so it is really no surprise there. I would say that they are just like anything else, come prepared and ready for a little discomfort and you should be fine.
As others have said, I've also found that once inside the building themselves, airports are more or less the same in most countries. They'll have their good and bad procedures that we all have to follow, and depending on the times of flights they'll either be exceptionally busy or extremely quiet. Indian airports are the same as any other and landing in a major airport in an Indian city will be like landing anywhere else in the world, so there's nothing to worry about in my opinion.
The major international airports in India are very nice, and I believe they recently had some new terminals come on line only a few years ago. They should be in keeping with your expectations. Smaller airports will be quite different, but it is unlikely you will go to them.
