I downloaded the Android app for Wikipedia and had a play around with it. One particular bit gave me a bad experience/first impression, so here's some feedback for you.
I was completely puzzled yesterday when I tried logging into the Wikipedia app for the first time. I added my login, password and then hit the checkbox to remember my login.. only then to realise my password was not visible in plaintext and that the label did not say remember my login [1]. Now this password I use on a couple of sites (I know that's bad but it's the case here). I never write it anywhere, it's engrained in my memory. So to see it there in plain text freaked me out and I was suddenly weary that I was in a public space where people could see over my shoulder and to be honest I felt really violated. I've now changed that password.
This was a really nasty experience for me. I'm trained to check those remember login checkboxes, just as on a signup form I'm trained to uncheck the add me to your mailing list box (which some forms abuse) and check the i agree to terms and conditions boxes. I never read the label.
I don't really get the need for such a feature though. No login forms on the web in website or app form that I know of have such an option as `show password` (please point me at some if they exist). It's not clear to me what this achieves. It doesn't help me remember it for example... all it seems to achieve is to give the impression that the password is not important and can be shared.