I got myself a pair of ben wa balls for valentines day. They're wonderful! I opted for these
Ben Wa Balls in Blue Box
I was back and forth between the larger balls and these smaller balls for quite some time. I am really glad I opted for the smaller ones. I am no pro yet. I can only manage to keep them in for about 10-15 minutes at a time. There is a nice sensation when I tighten my pc muscles around them, but if you're looking for pleasure they aren't the way to go. They certainly won't bring you to orgasm by themselves.
Everyone's different inside I suppose but I am confident in telling you they certainly will not get stuck. If you're comfortable putting them in then you'll be comfortable taking them out and its not difficult at all. If you simply loosen the pc muscles they should come out on their own.
I am using mine to prep for child birth as I am going all natural and will gladly post more about my experience with them later.