We popped by several locations across the island to check if M1's 4G coverage was available. Well, let's just let the pictures speak for themselves.
Our random drive around Singapore revealed that M1's 4G LTE network is a little short of nationwide coverage. As you can see from the screenshots above, there are a couple of locations (along Lim Chu Kang Road and Sungei Dekar) where there was no 4G signal. Granted, these two locations are quite deserted and we doubt anyone would visit these places regularly.
Other than these two locations, we hardly found any blind spots when traveling around over the weekend. The MRT stations that are above ground all had 4G connectivity, although this doesn't necessarily equate to having a stable connection in the particular area, town or during the journey to the next station.
There was one particular location in the vicinity of Suntec City that we were unable to get 4G signal. After a long day of traveling around the island, we decided to have our dinner at Paulaner Brauhaus German Micro Brewery Bar around 8 pm. We checked the phone and noticed that there wasn't any 4G connectivity.
M1's nationwide 4G network will be made available from 15th September. For early adopters who are signing up for the 4G plans, you may want to share your findings on locations in Singapore with 4G connectivity here.
Basically, it is a public Google Maps where anyone can pin a location on the map where there is 4G connectivity. A group of HardwareZone forum members has created one for SingTel when it launched its 4G network in June. SingTel's 4G subscribers can contribute to the map here.