Product review (5 stars): Ideal for my application
This is an initial reaction, as the item came today.  My particular problem is that I have a hot tub that was allowed to cool off when a breaker tripped.  It has been very cold here, and I was lucky to catch it in time.  I thought it would be a good idea to get a device to monitor the temperature from inside, and I bought this and a Ambient Weather F007PF 8-Channel Wireless Pool and Spa Remote Sensor, and another regular sensor for a dome to cover the hot tub which will be arriving shortly.

These all run on AAA batteries, not included.  The set up is easy, using DIP switches like the old garage door clickers.  Everything lit up properly when the batteries were put in.  There are LEDs on the remote sensors to confirm proper operation.  The display on the remote sensors has a Channel indicator, so you can see that you have it right. My hot tub is on Channel 1, which works out well. The backlight can change colors based on the indoor temperature, or the temperature of the sensor on Channel 1.  The default color for more than 100*F is red, and it changes to orange if the temperature of the hot tub drops below that.  So with a casual glance across the room I can verify that the power is on, and the heater is functioning.

The display is big and bright, and the level of backlight can be easily adjusted.  Like other LED displays, there are some angles from which the display cannot be read, mostly below straight on.

The instructions say that you should have a line of sight from the floating sensor to the base unit.  I don't really have that, and yet the remote sensor has not failed to transmit data to the base station since I turned them on.  There is a note that if you have a cover over your hot tub, do NOT get a floating sensor with a humidity sensor.

The manual is satisfactory, and can be downloaded.