Jewel of India is consistently rated the Best Indian Restaurant in the Upper Valley. I'm pretty sure that this is because there isn't much competition. The food is pretty bland (unless you tell your server that you want it really, really, really spicy and even then you're likely to get something that doesn't have much spice).
The samosas at the Jewel of India are probably the only good samosas in the region. There are other places in the Hanover area that sell samosas, but they all seem to be made by the same company and come in flavors like "cheddar cheese and sunflower seeds," and even the ones containing peas, potatoes and other "normal" samosa ingredients have a funny aftertaste.
On Sundays, the Jewel of India has a popular lunch buffet for about $9. It usually has a number of vegetarian dishes (including a couple of vegan options, like chick peas, rice and lentils). On Monday-Saturday, the Jewel of India has lunch specials on regular menu items. All of the portions at Jewel of India are huge, so the lunch special is probably a better deal than the buffet (unless you eat a ridiculous amount of food).
The Jewel of India is one of a very small number of restaurants in the Hanover area that has multiple vegan items on its menu.