I like that app, not bad for your 1st one.
Since you are asking for suggestions, I have some:
1- Add a little bit of "color" to it, having either black or white screens make the app unatractive, I'm not saying your app is bad, I mean, you have to put some "eye candy" but not too much.
2- Your views (such as buttons, editviews, etc) get a "standard" size throughout your app, in other words, make all the buttons the same size, all the editboxes the same height (if applicable of course) that gives a sense of uniformity and pleasing to the eye.
3- Your "About" box, make it a little bit more interesting, the way you have it (see attachment) is kinda confusing.
4- Focus on a few things at a time, meaning, work on features first and looks second or viceversa, that way you can plan and really improve your app which by the way is good for a first app as I mentioned in the beginning.
I hope that helps you a little bit.