It can also be used for general serial applications. This board still brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded. This is a really nice feature to have and allows a sketch to be downloaded without having to hit the reset button. This board will auto reset any Arduino board that has the reset pin brought out to a 6-pin connector.
The coolest thing about the FT231X Breakout is that we have broken out ALL the pins for your use, making this board all the more hackable! It also uses a common microUSB jack.
One of the features of this board is a jumper on the back, which allows the VCC output to be configured to either 3.3V or 5V. This board ships default to 5V, but you can cut the default trace and add a solder jumper if you need to switch to 3.3V. It should be noted, however, that the max input of the FT231X is only 3.3V but it can operate down to 1.8V with external pull ups and is also 5V tolerant.