yes. it can be that hard to reboot. i wouldn't pay a dime for an app like that. its a alpha release, beta at best. yes the dev may get it working 100% but what if he doesn't? in your link he tells people "it works as advertised". he may be a great guy and get everything working but this is the interweb afterall.
i was lucky enough to get my phone rooted. the free app "lamppu" does what you want and gives you a handy on/off widget. the superbright setting doesn't work but it's bright enough. but again, you need root for this one.