The "quick note" field on the toolbar lets you type out a few strings of text and simply tap your keyboard's Return key to save. This is perfect for quick reminders that don't require any formatting at all.
When you tap the voice button, the app "listens" and transcribes anything you say into a text note, which is obviously a convenient feature. If your device is running Android version 4.2 or higher, Keep will also record what you say and even keep it embedded in the note. This is perfect for notes that contain audible elements that simply cannot be transcribed. Those with Android devices still running Ice Cream Sandwich or lower, however, are out of luck, as the app can only perform the transcription sans recording.
While the photo notes option is certainly convenient, it does have one huge flaw: it forces you to take a new photo. As in, it doesn't let you use existing photos from your Gallery, which doesn't make any sense at all.
If you're into taking really detailed and meticulously formatted notes, then Google Keep will disappoint you. With its simple text box, you can add line breaks, check boxes, and photos, but nothing more. There are no font choices, text colors, or bold and italic options, and there are no modules for inserting video or location tags. To be fair, I would've been really surprised if Google had included all of these features right out of the gates, but it is still worth mentioning. As it is now, Google Keep is meant for quick and dirty scribbling, for things like grocery lists and quick reminders. Speaking of reminders, why isn't there a reminder alarm built in?
If you want to organize your notes, the app offers a nifty color picker with eight colors to choose from. Personally, I like this system, but I can see how others might be pining for Google to add extra tagging and category options. Good thing is that every note is searchable using the Search tool on Google Keep's dashboard, so whether your notes are organized or not, you should be able to find what you're looking for.
Even though Google Keep clearly has a lot of kinks to work out, I actually love its simplicity. I appreciate the home screen widget from which I can quickly create text and photo notes. And I feel more compelled to use the app regularly, since I know that it won't ask me to tag or categorize things. That said, if you're looking for anything beyond a basic note-taker then look elsewhere.