In my shop it has radiant heat, heats up very quickly, maybe 10 minutes and you can take your jacket off. Best way to describe it is it can be 40 degrees outside but if the sun is out and your in direct sunlight it feels a lot warmer simply because the of the sun rays.
My heaters work the same way, it doesn't heat the air specifically, but heats the objects in the room which heat the air, hence the name "radiant heat". After 10 minutes they are plenty warm to work.
In my garage (separate from shop) I have an air heater/fan and it feels totally different. With the air heater if I open the garage I feel like all the warm air is gone, with the radiant it doesn't feel as cold because your still being heated. I notice my hands get cold in the air heater rather than the radiant heat.
Here's the shop setup. Probably a bit overkill for a smaller shop but I have seen radiant heaters that curve around the shop so you only need to run one.
Thermostat
Heaters