HNML are prepared in an Indian style. In my years of ordering special meals, I find HNML more appealing than the Muslim meals in terms of variety and flavour. I've had dhaals, curries and even a chicken marsala for breakfast, lunch or dinner. The main is usually rice, naan or more commonly prata which is what we eat in Singapore. Special kudos to the authentic achaar and pickles that just adds that special touch to a delicious meal.
Most importantly, you are served your special meal first ahead of everyone else in economy.

If you like some variety on your long haul, I would stick to the inflight menu on SFO-SIN and only order HNML on the SIN-HKT segment. I find the catering ex SIN far superior than its outstations.