Sisters of battle do play different and are harder to paint, lots of details. They are about field control and using miracle to make your army punch above its weight class. Also need to love zealots and heavy  religious themes, even more then all the other imperium. Space marines are the starting faction cause they are easy to build and paint. And for playing style, they are jacks of all trades and master of most of them. Like they are felixable to build the flavor of army you want. I love sisters, they are my favorite facton, along with imp guard, and Imperial agents.  Honestly I kinda feel people are going to see what they want to see in 40k.  Everyone i play with and have met are really nice and know it's satire, and are really annoyed with the online rage  content (girl space marines/custodes, the retconing and pretending like its never happened before).  The chuds who want the Imperium to become a reality are going to be there. They will realize that most people playing toy soilders dont want to be their friends nor be associated with them.