My one problem has been with removal. I can remove it fine without pain and stuff, but I keep spilling it in the process of pinching the bottom of the cup to break the seal/grab hold of it even though I'm trying hard to keep it upright. When I start pulling it out, it very easily tips and spills (luckily I was in the shower at the time!). It's like I don't have enough fingers to both grab the cup and keep it stable on the way out.
What do you guys do? Do you sit on the toilet while removing so that it spills directly into the toilet? Or do you manage to remove without spilling?