adventure? in the original meaning of that word (read, Monkey Island, Broken Sword or Longest Jounrey) no, not at all. It even is not your ordinary Myst game.
Uru is a slight departure from the original Myst when considering the puzzles. You still have to wander around, collect all the different hints you encounterand and then solve several mysteries in the different Uru ages. Sometimes is even more jump n' run then solving mysteries.
But this has nothing to do with adventure games like the "longest journey" you played. Myst worlds are empty spaces, no humans to interact and no animals to encounter.
Don't buy this if you expect a longest journey. Both games have nothing in common. Rather look for Syberia 1 and 2, Broken Mirror, Broken Sword 3 to name just a few recent real adventure titles.