The visuals of ECHO are among the game's best attributes. The authentic looking cave paintings, wild animals and even the way shadows play off of the wall when there is a fire lit all help to pull you into the game's prehistoric backdrop. The first-person angle with free pivot/rotating capabilities almost reminded me of playing games like Myst III, which works, it just seems a bit outdated at this point. The cutscenese are beautiful and are stunning pieces of work in themselves -- unfortunately there were plenty of times when I would get a lag or other frame-rate issues while watching them. This is a bit disheartening since my Radeon 9800 Pro should be well within the specified requirements.
The game's music and sound effects also lent themselves well to the game's setting. The background music was a mix of percussions and earthy-wind instruments giving the game a very tribal feel, while the sound effects like the crackle of the fire or growl of an animal also seemed dead on.
Where the visual surroundings and secondary sounds really help to draw you into the Paleolithic Era, the voice acting (or maybe just the script) yanks you back out. It isn't that the voice acting is bad, though it is a bit stiff at times, it's that the words and phrases they are saying make the characters seem a bit too... educated. The characters just seemed less like cavemen and more like modern people who like to run around in animal skins and live in the mountains and woods.