Players report that Book of Thor by Devbox offers an engaging Norse mythology-themed experience with visually appealing graphics and an atmospheric soundtrack. The game features a classic 5-reel layout and incorporates the popular expanding symbol mechanic, which players find enhances their chances of landing significant wins during free spins. The community appreciates the potential for high payouts, especially when players land the special Book symbol that acts as both a wild and scatter. While the gameplay is generally smooth, some players note that the volatility can lead to extended dry spells between wins, which may test the patience of less experienced players. Overall, Book of Thor is seen as a solid entry in the free-to-play slot market, offering a balance of excitement and thematic immersion.