There are so many great browsers out there - such as Firefox and Opera - that I don't see why anyone would choose something like Lightbrowser, which is basically an extremely light and limited browser.
However, I can see situations where it may come in useful, for instance when you're using a particularly CPU and RAM heavy application that prevents your default browser from working very well. Lightbrowser is about as basic as it gets - about the only thing it offers other than browsing is the possibility to add bookmarks. The developer's claim it is the lightest and fastest browser out there and while I wouldn't argue it's the lightest, I'd question whether it's the fastest although it is certainly seems to be.
You can add bookmarks using a button in the bottom right hand corner, but these are only limited to a handful. Perhaps the only other feature of Lightbrowser to speak of is the user agent changer. This allows you to change your user agent, which means that if you come across a website that's only for Windows or iPhone, you can still view it in Lightbrowser simply by changing the agent. There were some instability issues however - when closing down Lightbrowser, it crashed completely.
Lightbrowser is for all those that need an extremely lightweight browser that takes up hardly any CPU or RAM but not much more.