First impressions of the device was really good. Device and remote is well built, I liked the fact that battery terminals on remote are metal pistons instead of springs seen on other electronic devices. User interface, 4K features and apps are all great. I bought this device specifically as it is an HDMI based 4K device intended for big screens.
Problem: I am using an Epson ultra short throw projector which uses a bluetooth/radio frequency based remote, and it does not have a traditional Infrared(IR) Receiver and amazon firestick remote uses IR for volume control, mute and power buttons. Rest all buttons on firestick remote are based on radio frequency!!. That means, for power and volume I have to control it on projector. Read further if you need more details.
Companies are moving away from IR remotes as radio frequency based remotes can be operated from anywhere in the house and it does not have to be pointed at the device. This is the case with most modern projectors. Fun fact is, fire stick remote also is using the same technique except for few buttons. Whoever designed the firestick remote thought its a great idea if it can be customized to control traditional IR devices connected to firestick and for this reason they have included an IR blaster. Idea is great, as it would mean you need to use only one remote - firetv remote to switch on and operate both TV/Projector and firestick itself. But the IR option should have been restricted to power button only, not the volume or mute buttons. As these functions are not included in the radio frequency mode, I still end up using both buttons on my projector/remote + firestick remote. I called the customer care and they explained how the '4K device is not suitable for projectors'. What 4K TV that size is not a smart TV these days? Whats the point of using a firestick then? :D Luckily for me, my Epson is HDMI CEC compatible and it's remote can control most navigation on both projector and firestick! This might not be the case for you.