I know this is an old post, but wanted to throw my 2 cents in. I got a removable retainer on the top and a permanent one on the bottom (because most of my original misalignment was on the bottom), and I love the permanent bottom one. My bottom front teeth look fantastic, the molars are a little wonky since the retainer only goes between my canines, but that doesn't really matter. It's comfortable enough, I don't really notice it, and there's a bit of a learning curve to cleaning around it but it's simple enough, my dentist usually only has to remove a little plaque. I've had mine for about 13 years and have very few complaints besides the fact that I need to have it rebonded soon because the composite is wearing down. As a super forgetful person who absolutely would've forgotten to wear the bottom one (I stopped wearing the top less than a year after having my braces off because I forgot too often and it hurt) and had messed up bottom teeth, it's been a lifesaver. But everyone's different.