The Happy Hacking Keyboard Professional 2 is a keyboard with a reputation, and it lives up to it. The HHKBs originated from a collaboration between PFU and Dr. Eiiti Wada, a Japanese computer scientist who was unhappy with existing solutions. His research led to the current compact layout. As the name hints, it was designed with programmers in mind, particularly emacs and vims users.
Pro Compact & minimalistic
This keyboard uses a 60% layout that forgoes unneeded keys and merges the extra set of keys into the Fn layer. This mimics the behaviour found on most laptops due to size restrictions. Despite this, the more commonly used keys are left intact so that one does not feel too unfamiliar with the more compact layout. In addition to reducing the keyboard's size, it makes accessing virtually every key on the keyboard a breeze.
Pro Fluid key feel with Topre switches
This keyboard’s keys use Topre switches, which have a smooth, interesting feel: each key’s resistance is quickly lost once it starts being pressed. This sensation is accompanied by a unique and pleasantly organic “thock” sound. These hybrid switches have both a rubber dome and a spring which create the initial tactile bump feel and subsequent continuous action. If you want, these switches can be silenced, either by the manufacturer before purchasing or by following some DIY steps (easy to do, but time-consuming).
Pro Designed to keep you in home row
Eiiti Wada (a Japanese computer pioneer), the co-developer of this keyboard, is a UNIX user and wanted to make life easier for programmers, particularly vim and emacs. He aimed for a keyboard layout that allowed fingers to stay in the home row most of the time. For example, he placed the Control key where the Caps Lock traditionally is. Most *nix users and general power users know that Control is used more often than Caps Lock for various shortcuts. Therefore, this key repositioning makes sense, since it makes access easier, using the pinky fingers while keeping one's hand on the "home row" of keys.
Pro The keycaps are made from PBT and the inscriptions are dye-sublimated
PBT plastic is a very brittle material that is able to withstand high temperatures, doesn't yellow or wear out easily. The dye sublimation process ensures the inscriptions don't wear off easily (compared to pad printed ABS, for example). This process usually requires keycaps to withstand high amounts of heat for the ink to transfer from one material to the other, something that's not possible with other commonly used plastics, like ABS. Dye-sublimated inscriptions are also better than laser, etched, or engraved inscriptions in the sense that they don't get dirt or dust as easily.
Pro Easily programmable and highly modifiable
This keyboard comes with the standard DIP switches to modify key behavior, but you can also completly swap out the controller board or even fork the TMK firmware to make your own keybindings in the firmware. Also available is the TMK controller board custom made for HHKB users.
Pro The arrow keys, the page up/down keys and the media keys, among others, are easily usable via the Fn key, comfortably within reach
Even though there aren't dedicated keys for these functions, they can be easily used by pressing an easy-to-reach Fn key, placed just below Enter. Functions accessible via the Fn key are printed on the front of the keycap.
Con No metal backplate
The HHKB lacks a metal backplate. Most decent mechanical keyboards have a metal backplate that is usually mounted to the underside of the PCB. The inclusion of such a plate, aside from increased build quality, adds more stability by dampening vibration during use.
Con Lacks versatility outside of typing
The Pro 2’s design focus on typing and coding results in compromises that hinders other kinds of uses. It’s not an ideal keyboard for gaming: many games use the Function and arrow keys extensively and with the Pro 2, that requires double strokes or completely reconfiguring the key binds to fit the layout. Also, when it comes to crunching numbers and spreadsheet work, the absence of the arrow keys and a dedicated number pad makes this keyboard completely cumbersome and inefficient to use.
Con Manufacturer warranty is only valid under certain conditions
The warranty conditions specifically imply that the one year manufacturer’s warranty is only valid within Japan or if bought within the US from elitekeyboards.com. For all other countries, the warranty is considered void by default.
Con Lack of keycap/switch customization options
Due to the nature of the Topre switch, customization is very limited. On other keyboards, like those with Cherry MX switches, it is easy to swap switches. With Topre switches, this is only possible if a keyboard with the right set of rubber domes/cups is bought. This leads to a higher customization cost.