Very handy, and has potential to be better
I'm a lighting designer and I like this app, because I can take a photo (day or night) and do some quick ideas to how I would use light in a space. It saves time of having to take a photo, upload on my computer, Photoshop it, and then upload it back on to my mobile to show someone, and I can make changes instantly.
Some features that I think would greatly improve this app, would be to have more color options instead of just the cool white, warm white, and blue. A color mixer would be good. Also more light options such as dots/circles to represent recessed fixtures or even just exposed bulbs. In my opinion, those would be a good start to make this more useful to designers.