I use LightShot a lot, as it's the easiest way I know of photographing (and optionally annotating) whatever is on your computer screen. The hotkey to make a screenshot defaults to the "PrntScrn" button, but I set it to "Ctrl-\" (control-backslash) instead, as that's an unlikely key combo to hit by accident.
As for problems caused by LightShot, the only problems I've encountered are, it tends to cause errors in MMORPGs (eg, Toontown Rewritten or Wizard 101), and in virtual worlds (eg, Second Life), because it has hooks in all video streams (acts as a "filter driver" for video, I think the technical jargon is), so that it can freeze and capture what's on your screen at any time. So, if doing anything video-intensive (games, movies, etc), it's best to turn LightShot off (right-click the purple feather in your system tray and click "exit"). Other than that, I leave it turned on all the time.