Texture packs is a huge thing for the standard version of Minecraft, with higher resolution texture packs that change the look of the game. A lesser known fact is that this feature is also available on Minecraft Pocket Edition, though the procedure to do it is a bit more complicated.
You can get texture packs for both Android and iOS versions of Minecraft PE. For Android, a companion app called BlockLauncher will allow you to just point it to a texture pack .zip and that’s it, though there’s a disclaimer that it might not work on all devices. It did, however, work perfectly for me.
For iOS, there are both jailbreak and non-jailbreak methods. The non-jailbreak method involves the now-famous iExplorer method of accessing the file system, and the method is described here. The jailbreak method simply allows you to do it all in iFile rather than having to use a computer to browse the files, and is otherwise the same in just copying over files.
The actual texture packs can be found online. I tried BDcraft since that’s what I use with Minecraft on the PC, and it’s available here (make sure to scroll to the PE version). Another source that contains more texture packs can be found here.
The difference is quite noticeable, though of course that depends on which texture pack you choose. BDcraft seems to have a minor bug with torches on both the Android and iOS versions I downloaded, but otherwise worked well.
While Minecraft PE still hasn’t caught up with the PC version, it does get frequent updates with tons of new features, and I know some play it quite a lot. With this trick you might just be able to improve the look of the game a bit, and that’s never a bad thing.