Sometimes it's half the screen size, which means there is an empty space at the bottom of the page where I can't swipe left/right to go to the other slide, coz it's not part of the slide height.
I think, this is wrong, I am pretty sure you can set in css the height of the div for being at least 100%, and if it is more you can do a scroll or what you want, or by using ion-pane.
(I did something like this for my app, so I know you can do it with simply html and css)