I have never been a huge fan of many of the portable bluetooth keyboards being sold out there. Logitech and Microsoft both make some of the better ones, but even those felt small and crowded at times. I was just browsing on Amazon last week and a keyboard from Anker popped in my recommendations.
On sale for $19.99 I just went and ordered the Anker Ultraportable Keyboard. While it is a little heavier, and a little bigger than some of the competitors I love this thing. It feels and sounds like a true desktop keyboard. I have been using it with my iPad Air 2, but you should have no problem using it with any device. I have not used enough to test the battery claim since it says it can go 6 months on one charge. I obviously have not had to charge it yet!