You're talking about DOMS, Delayed Onset Muscle Soreness. It's where your muscle tears on a microscopic level. It isnt the sign of a good workout, it isnt the sign of a bad work out. But sometimes it can help lead to a problem if you dont go easy on the muscle for the next few days.
It's a satisfying feeling in a weird and sick way, nonetheless
Your muscles wont really get used to it as such, although you can do a few things to reduce the soreness:
-make sure you stretch well after your workout
-whey protein also helps cut down on the soreness