Very nice, comfortable and responsive... on all devices except the one I purchased it to use with. Connects, sincs, and works well with 1st gen FireStick, an older Windows7 laptop (using the included dongle), and even with my 5th gen Kindle Fire tablet.
However, that said, I purchased this to have better control over a recent Android TV box running Android 6.0.1. The box is supposed to have Bluetooth 4.0 running, but apparently thinks itself a phone, rather than a landscape oriented TV box. The keyboard is seen, pairs, then shows connected, but the TV box does NOT recognise any input from the keyboard. So pretty much useless for now.
Am trying to get info on flashing the box to a working Bluetooth protocol, but Chinese manufacturer, soooo...... We'll see.
So caution on this keyboard purchase. Currently does not work with M8s II android TV box running 6.0.1.

This little keyboard is amazing, but the directions that came with it left something to be desired. Based on some other customers (pictures/reviews) I wasn't sure if I were going to receive a unit with a removable battery and/or a BT dongle; it turns out mine had a BT dongle included and an integrated battery. I use this with my Android Smart TV box and haven't noticed any connectivity issues from about 15 feet away (it is very responsive). Maybe this is because the BT built into my TV box is better than the dongle that was included with the remote, which might be where some users are having problems. For the sake of improving functionality and reducing frustration, it might be worth spending $8-10 on a new dongle before sending this unit back and/or encountering the same issue with another device. I haven't looked at the specs of the included dongle, but that may be the culprit.

Findings (most mentioned by others already):
-It is lighter and smaller than I expected, but doesn't feel cheap. I was worried I would either be carrying a small brick around the living room or a squeaky/flexible piece of junk.
-The backlight is nice, but the Power/On light is too bright when watching in a dark room (I find myself constantly flipping over the remote as soon as I am done with it).
-Good button size. I have rather flat thumb tips and as such am a terrible typist on my smart phone, but this is perfect.

Since this is my first mini keyboard and smart TV setup, I had no idea what to expect, so my problems may not be issues for other people, but I thought I'd share my lessons learned.

Tips:
Fn+F5: Turns the screen off, but doesn't power down the TV box (still need to keep the stock remote around for that).
Esc: Same as Back button on stock remote (took me a while to realize this).
Touchpad Scrolling: Works like a smart phone/tablet (drag up to scroll down), not mouse wheel or laptop scroll bar (I'm still used to the old scroll bars on laptop touchpads).
OK Button: Works like a left mouse click, which can be frustrating. If you have your mouse over a selectable item, but navigate somewhere else using the D-pad, you will click on whatever your mouse pointer is still hovering over. Using Fn+F8 (disable touchpad) does not prevent this, it just stops the mouse from moving (continues to select whatever you left it hovering over). To get around this problem, you must move your mouse to a benign place before using the D-pad to navigate and select different items. Sometimes it can be annoying because a benign place on one screen will be selectable on the next. Users might just consider never using the D-pad unless just scrolling through the menus.

I purchased this mini BT keyboard to use with my M8S Pro Android media server and it really works well. I was concerned that it would be too small to use with my large fingers, but after using for a week I'm very comfortable with the layout and the keys. Much better to use than any other air mouse I've tried.

It pains me to have to write a negative review about a product that I like. That said, I placed a order for one of these keyboards. and when it arrived it would not pair with a known working device. Well, nobody's perfect. Let's just return this one, and order another. By now you already have guessed that the second one would not work. Exactly the same problem. This cost me five days waiting, and several hours of trouble shooting.

Order this at your peril. You have been warned.

Really handy keyboard! I use it in my semi with a tablet for the daily paperwork and e-mail chores I have. I'm using it right now actually. Its small and handy enough to throw in the briefcase, but large enough to not cramp up your hand with extended use. I have not had any connection issues any of these other reviews talk about, and I have tried it with my phone, tablet, bluetooth enabled laptop, and my desktop with the usb receiver it comes with. They all connected flawlessly. The "mousepad" is in a really good spot compared to some others that will have it on the side. The placement for it on the mini is perfect. Good bt keyboard, especially for the price!