Yes things slow down but the quality of print gets better. They are a blast and you can just sit and watch it print for hours . But they then can turn evil on you and suddenly print like crap , sometimes that is the filament whether you changed it or even if it is drying out some or maintenance on the machine itself like a plugged tip. Plus there are a ton of settings you can play with to change how it prints, you do tend to waste plastic experimenting but that's how you learn what it all does. I use Cura as my slicer, I did start out originally with Repetier but found the software very limited for settings.
I get what you mean with how they turn evil. The first time I changed filaments it took about 15 tries to get the filament to stick to the bed consistently. I've found that as long as my print sticks it will have no problem doing the rest of it. Come to think of it I don't think I've ever had anything go wrong after it got past the first 3 or 4 layers.