"The Great Wall" deserves to be seen on a huge screen and a great sound system. It is visually stunning: with vast numbers of soldiers in most scenes; the brightly coloured armour of the soldiers, red for the Eagle Army, Blue for the Crane Army, Yellow for the Tiger Army, purple for the Deer Army and black for the Bear army; the intricate design of The Wall; lighting that builds atmosphere, and monsters that are genuinely disturbing.
If you've seen other Zhang Yimou movies, like "Hero" or "House Of Flying Daggers" then you want be surprised that "The Great Wall" is a rich visual experience. The biggest differences are that this one is shot in China in English (mostly) and with a big budget ($135m).
Watching "The Great Wall" is a fun way to spend an afternoon, as long as you let go of any expectation of historical accuracy, which shouldn't be hard in a monster-flick. Give yourself up to it and it will make you laugh and cheer and feel the thrill of watching other being brave.