I only ever ordered room service on a semi-regular basis when in Thailand. Even at the most expensive hotels I have found room service to be comparable to eating at a regular restaurant. Heck, many of them don't even have any hidden service charges.

While I had concerns about other areas of the property, I would say my most reasonable in-room dining experience was at Trisara in HKT. IIRC, a CPK-sized pizza was only about $12 and no additional fees!