Straddling enthusiast and SMB, Thecus' N5200 Pro is a NAS that means business. It makes no apologies for what it is, and as such its appearance is that of a big black box, with five hot swappable hard drive trays facing the outside world and a blue-lit LCD giving status updates for network settings, drive health, and system health in general. There are buttons under the LCD to change what information is displayed, and to alter some settings — however, by and large it's tedious and unintuitive, and you're best to just stick to the web interface if you can.
The drives are held in by the only cheap looking part of the system — the silver quick release handles — and every tray can be locked via key, of which x copies are included in the box. Each drive has both access lights and power lights, so you can tell visually if one has failed.
A huge power button is on the bottom left, and below this a reset button. Above the power button is a USB port into which you can hook up external storage, a printer, or USB dongle for wireless capability and an array of indicator lights, for problems, USB copy LED, network activity over the two included gigabit Ethernet ports (one WAN, one LAN), and an upgrade light, showing that data is inaccessible.
The rear gives the first hint at what this box is truly capable of, with two USB ports, an eSATA port (for external storage alone, you won't be able to hook your PC into this), two gigabit Ethernet ports (capable of being load balanced or teamed), a USB type B port (for connecting to your PC as a mass storage device, but first you'll need to create a target USB volume) and a serial port (for UPS monitoring). While the 120mm fan at the back is acceptably quiet, it could be better, and the PSU fan is tiny and definitely noticeable in volume. Thanks to its medium pitch it never reaches the realms of truly annoying, but in the home it may vex some.
Hardware-wise the Thecus N5200B Pro runs off a 1.5GHz Ultra Low Voltage Celeron, with 512MB DDR RAM. For a bit more flexibility you can opt for the N5200BR Pro, which bundles a four-port gigabit switch, but as a consequence loses the ability to perform link aggregation. The non Pro versions use a slower processor, clocked at 600MHz, and only contains 256MB RAM, which will mainly impact both boot and RAID rebuild time.
The included software is easy to use, and was capable of adjusting the network settings of the device even when it was sitting on another subnet. As a nice addition, OS X software was supplied. Linux users miss out, an oddity considering the open source nature of a lot of Thecus' software.