If you want to take square snapshots and apply (sometimes) garish filters to them, there is only one choice—Instagram. The Intsagram app for Android is getting an update today to v6.10 with a few smallish feature additions. Well, heavy users of Instagram will think they're pretty great.
The discovery tab is now a magnifying glass icon because of reasons. When tapping on it, you get two tabs—photos and people. The photos tab is the same as ever, but the newly added people tab shows you accounts you might want to follow. The other notable change is the option to go back and edit captions later (fixing typos and whatnot). Previously, the only option was to delete the post and create it again.
The Android version is rolling out today, but it's still not live in the Play Store for me. Give it some time and you'll be editing captions and discovering stuff in no time.