My recent visit to Shivalli was one of the best, if not the best experience I've had in an Indian restaurant. We went on a weekday evening, when I think the buffet is unavailable, though I've heard good things about that too.
Our waiter was very helpful and attentive. Once we had informed him that 3 out of 4 of our party were vegan he offered to do us a set menu which consisted of a 4 course meal suited to our dietary requirements, which didn't appear to be on the menu, and it was really cheap!
All the food was amazing, really really tasty. In the past I've been disappointed when Indian food wasn't flavourful enough, none of that going on here though. Everything was delicious and also diverse, especially the selection of curries we had as a main. A scoop of vegan ice cream as a final course was a perfect finish, because our stuffed stomachs couldn't handle a bigger dessert!
Throughout the meal we had waiters coming up (though not TOO much), asking if everything was okay and if we needed more food items - as if they hadn't fed us enough anyway!
All in all, if you're in Leicester and you're hungry... like HUNGRY and you love Indian food then Shivalli is where you ought to be.