The new service is available both in your web browser and as an Android app. There's no mention of an iOS app but I would bet it is in the works.
Google Keep lets you jot notes down with the keyboard, and it also offers a halfway decent transcription of spoken notes. You could also take a photo and attach it to a note.
It's a bare bones note-taking service and this is most obvious when I try to tag or categorize my notes. I can set a color for a note and use that as a visual cue but there doesn't appear to be any way to attach tags or any other label. There's also no way to clip and attach a webpage, sketch and attach a drawing, or attach a video to a note.
Speaking of limitations, there's also no way to increase the font size or use basic note-taking skills like underlining or highlights. There also doesn't appear to be any way to italicize the text of a note or to make it bold. That last shortcoming will likely become an issue, IMO, because the background colors for the notes are visually strong enough that they tend to make it difficult to read the text of a note.
Unlike Evernote and MS OneNote, Google Keep is free. That is probably going to attract at least some users, and the fact that this service will soon be integrated into Google Drive will probably also please some who have adopted that cloud storage solution.
But frankly I don't see the appeal and I also don't understand why this service needed to be launched at all. Google Keep is a minimalist note-taking app. There are a bunchaton of apps in Google Play that are as capable as Google Keep. Did the world really need another one?
And in case you were wondering yes, I am still upset over Google Reader. That doesn't invalidate my opinion of Google Keep, but it does remind me that we can't trust Google not to rip the rug out from under us. If anything the demise of Google Reader reminds us that it is much safer to use a third-party app that isn't dependent on Google's servers. That's why I am not going to use Google Keep.