I think it's safe to say that most BlackBerry users are rather keen to send or respond to messages as soon as possible - even if walking, and that's where TextNGo may come in useful. Essentially that is what the app is designed for - to allow you to see where you are going even if typing a message on your BlackBerry 10 phone.
TextNGo utilises the camera application on the BlackBerry so the bottom half of your screen on the Z10 will contain the keyboard and the upper half will be the camera, but over the camera interface is where you can see the text you are typing - clever stuff. Once you have written the message it is just a case of pressing the share icon and you then select which service you wish to use from the BlackBerry Hub. The text you have written will automatically be present in the message when it opens, so it is just a case of selecting the recipient and pressing send.
The camera flash can also be on for night time use although I didn't test how effective this was. I must stress that the app is designed for walking and should not be used when driving - that would be crazy.
Although I won't use TextNGo that often (as I don't get out much) it will come in handy at times and I will be keeping it on my BlackBerry for those occasions. If you fancy picking it up the app is priced at £0.75/$0.99 so it won't break the bank.