The key game element which makes this cool is that different regions spawn different monsters. For example, in Seattle there might be a lot of slime monsters, and Fire monsters might be rare. In Phoenix this might be reversed. That means if you find a fire monster spawning ground in Seattle it is a valuable discovery and you want to share that location with your friends. The most important items you buy are things which extend your range, for example, roads and airlines. Traps are also interesting - if I rarely make it out to my parents house, for example, I can set a trap up there and collect when I do visit - or have a friend down there collect for me.
The combat is simple - each monster has behaviors that make it a different challenge to catch, for example, slime monsters leave a trail you want to avoid. But this isn't a game about combat, so the combat isn't complex or time consuming. There will be exceptions - there will be boss monsters that are tougher, and mega monsters that require friends to help take down.