[1 x MicroSD] I have used the ORIGINAL Gen1 cloud key to manage 3 access points and 2 switches for 4 years. It worked 'OK'. But it definitely had some features that I didn't like. When it wouldn't perform a firmware upgrade last month, I decided to purchase the Gen2 key. It has worked very well. I especially like the built in battery which was one of the things that that my Gen1 didn't have. If you are using GEN1 keys, you will find this product to be far superior.

[CE, FCC, IC] This is one of those things that sounds like a great idea (and it is) but also seems like it should be simpler to configure than it actually is.

To be fair, i've a background in IT, so I was able to stumble through it easy enough but still some cursing was heard during the process.

UBNT's management software is a breath of fresh air compared to dealing (years of ) other primitive WiFi systems, tons of configurability in it (so much so that I may never use of all it). 
It can be a little temperamental but it will reward you if you are patient. Once it is set up properly it requires very little hands on time afterwards.

Some dives through Reddit, UBNT's own community forums did answer some questions I had about the setup during the process.

You will want at the very least a multi-port (preferrably a POE+) switch to make the process simpler. 
Setup tips:
One UBNT A.P. and the CK Gen 2 must be on the same switched segment during setup so that configuration and provisioning may occur (or this will not work). Internet access is not mandatory during setup but it helps.
Cloud (remote) access and management are optional for the security minded crowd but they are available.
The device may be configured by phone or tablet APP, or logging into the device VIA it's IP address in a web browser with the correct port.
Doing this some other way than web browser may lead to an inability to log into the device.

For experienced technical trades people and adventurous self teaching individuals, this is a cool product!
 
A heads up for the non-technical crowd: 
I don't recommend this product for you, stick to buying your vanilla wireless solutions from whatever your preferred source is. This kind of product is not intended for you.

[CE, FCC, IC] This is one of those things that sounds like a great idea (and it is) but also seems like it should be simpler to configure than it actually is.

To be fair, i've a background in IT, so I was able to stumble through it easy enough but still some cursing was heard during the process.

UBNT's management software is a breath of fresh air compared to dealing (years of ) other primitive WiFi systems, tons of configurability in it (so much so that I may never use of all it). 
It can be a little temperamental but it will reward you if you are patient. Once it is set up properly it requires very little hands on time afterwards.

Some dives through Reddit, UBNT's own community forums did answer some questions I had about the setup during the process.

You will want at the very least a multi-port (preferrably a POE+) switch to make the process simpler. 
Setup tips:
One UBNT A.P. and the CK Gen 2 must be on the same switched segment during setup so that configuration and provisioning may occur (or this will not work). Internet access is not mandatory during setup but it helps.
Cloud (remote) access and management are optional for the security minded crowd but they are available.
The device may be configured by phone or tablet APP, or logging into the device VIA it's IP address in a web browser with the correct port.
Doing this some other way than web browser may lead to an inability to log into the device.

For experienced technical trades people and adventurous self teaching individuals, this is a cool product!
 
A heads up for the non-technical crowd: 
I don't recommend this product for you, stick to buying your vanilla wireless solutions from whatever your preferred source is. This kind of product is not intended for you.

[1 x MicroSD] I bought this to replace my gen 1 Cloud Key. It has a few key features that the gen 1 does not. The most important being that if it senses that power is out it will shut itself down. The GEN one cloud key has an issue that if it lost power it could corrupt the site info stored on it.

The gen 2 also has mush better specs and internal storage so no need for the micro ad card.

[0.645 lb] The Cloud Key (Gen 1) works the same. But the battery and memory card will save you more headaches from unplanned power outages and reloading that will be greater savings than the price difference.

[Aluminum] Quick set up from back up. Works great!

[6.07 oz / 172 g] This device provides local management for all my UniFi devices that I can access remotely. It took only 3 minutes to setup, but you should have a POE port available to power the device since it does not come with a plug.

[6.07 oz / 172 g] This device provides local management for all my UniFi devices that I can access remotely. It took only 3 minutes to setup, but you should have a POE port available to power the device since it does not come with a plug.

[Aluminum] love the live data readouts on this device, love the ease of use

[CE, FCC, IC] Straightforward method for setting up a UniFi controller without a server on the premises.