Compared to the recurring costs to maintain support / licenses with Cisco or Aerohive, Unifi products NEVER require additional licensing costs to operate or administer. In todays age of technology advances, it's a pleasure to work with a product line that has a unified admin …
Aruba Instant On AP Series Access Points are well suited for a small to mid-size setup (i.e., from 20 users to 500 devices that need to connect to WiFi). Aruba provides access points for both indoors and outdoors (e.g., commercial spaces and offices, and manufacturing units as well). Aruba Instant On AP Series Access Points can also support controller-based architecture, and I would recommend going for that when the AP devices are more than 30.
Ubiquiti is well suited to not just indoor WLAN access, but also outdoors. In fact, the range of the outdoor applications, while maintaining throughput is astonishing. I would say this is not a solution for a 1-5 person small office, due to the costs.
Management of devices has become much simpler with the UNMS application, but personally, I would like to see some AirMax-like devices from their Unifi line where everything could be managed from an Unifi controller.
Most Ubiquiti devices are 24V PoE, which is the bane of my existence. I have had several devices fried when staff plugged into standard 48V PoE. They generally don't fail catastrophically, either. You just get strange issues that are difficult to diagnose and eventually need to replace them.
Devices seem to have trouble with many patch cables/switches. Make sure you certify any patch cables you make and don't over crimp.
Sending devices from the factory with same 192.168.1.20 IP instead of DHCP makes it a pain to bulk-setup devices.
Ubiquiti makes great Access points at various tiers provided far better coverage and throughput than consumer-grade wireless repeaters and routers. We have not had any performance complaints from guests or from the administration who use the wifi on a daily basis.
Ubiquiti's support is basically non-existent by design. However, their forums are a great resource if you are willing to do the research and ask questions. Keep in mind Ubiquiti sells hardware, not support so the responses will be from the community of professionals also using Ubiquiti just like you.
We have used products from Netgear, ZyXEL, Cloudmesh, Datto, Mereki, and EnGenius previously often choosing products based on a specific situation, since starting with Ubiquiti [WLAN] we have pretty much stopped [usage] of all other vendors in the networking field and standardized which better allows us to stock spare equipment. Best part is if you need to replace equipment it is easy to swap it out quickly as the controller also acts as a live configuration backup.