I've previously mentioned that I do not like rain shower, here I would like to explain why.

No doubt rain shower is a cool item to have in your bathroom, but you might want to consider the cost of it before revamping your bathroom to have this facility, especially for HDB owners.

For me, I do not like rain shower, but I stay in a Condo where water heaters were already installed by the developer, so I would stick to water heater and rain shower set.

The reasons I dislike rain shower are:

1) Its cost, a water heater would cost at least $200, a set of rain shower with  conceal mixer, shower head, connecting nod and etc would cost close to $300, you may refer to my earlier post here.
2) Again, the cost! The cost of maintenance is high. I've recently repair the diverter for one of my rain showers, and it costs me $123 inclusive of labour and GST (I'll have a separate post on this), I remember a new set of electronic water heater with shower head is only around $160 to $180.
3) It takes longer time to heat up the water compares to electronic water heater, as this type of water heater tank is bigger and it heats the water and store inside the tank, whereas electronic water heater does not store the hot water, it just heats and use as and when you on the button.
4) As it takes longer time to heat the water up, you'll need to let your water run from the rain shower for about 2 to 5 minutes to get the hot water, it thus wastes the water.
5) When the water heater is on, it heats the whole tank of water, thus higher electronic consumption.

Having said that, I would still install the rain showers in my bathrooms if given a chance again, the reasons are:
1) It is really a cool and clean design, you'll need it if you want the classy look of a hotel liked bathroom.
2) It saves up space for my small size bathrooms.
3) The water tank heater were already build in by the developer, no extra cost incurred to install the water tank, but if I were to stay in HDB, I would  rather choose electronic water heater.

I hope the above give you an idea of the pros and cons of a rain shower and help you in your decision making :)
The little nod pointed by the red arrow is the diverter which costs me $123 to repair. This diverter functions in changing the water flow from the handheld shower head to the rain shower head and vice verse.