When living in Zurich we tried different indian restaurants, but Vulkan was the only one we visited more than once (surely about 8 times). Vulkan is (or maybe was) also the only one with an original tandoor oven in Zurich. The atmosphere is cozy and the toilets are clean =).
The service was always great, although it might be confusing for some people that some of the waiters prefer to speak englisch instead of german/swiss german.
The dishes were very delicious. As a starter I recommend the marinated lamb (although I am ordinary not into lamb!), but recommending a main dish is very difficult.. the ones we had were all very nice (always with Naan and Raita as side dishes). We were only disappointed once.. the food was totally not as it used to be.. something must have been wrong with the chef or he was not there?!
The prices are definetely adjusted to the prices in Zurich, which you get used to when you live in Switzerland.. lets say what you get here are dishes for an "average swiss price".
If we should ever be back in Zurich, we will definetely go back to Vulkan!