I would describe Google Keep as cute, Evernote-lite note taking application. It has the basic elements of Evernote (creating notes via text, voice or photo; tagging; archiving; cloud access on any device) but its not as in-depth and doesn’t include the new “Reminders” functionality of Evernote.
The way I use Google Keep is to keep track of short-term notes or lists. I like Evernote for things that I want to keep forever. But when I get a list from my wife for the grocery store, I don’t want that stored in Evernote forever. So I would use something like Apple’s Notes app when I had an iPhone, but I wasn’t happy with that because obviously it was only useful on Apple devices and I might need to access that list on a different device.
Enter Google Keep. I use it primarily on my Samsung Galaxy S4 phone, but also on my iPad Mini and Macbook Pro.
I also use it as a short-term to-do list. For instance, if I have a list of home projects I need to work on over the weekend, I’ll use Google Keep to create checkboxes that I can work off of as I complete my list. Again, this is something I wouldn’t want to store in Evernote.
I’m sure these use-cases aren’t what the Google team had in mind for how people should be using Keep, but for me its a useful tool when used in this manner.
PS – Oh, and I like how you can colorize the notes in Google Keep. It’s goofy, but I like how they do that and I enjoy the user interface overall.