The game has good re-playability, though it can get a little samey samey after a while. As to challenge, it is not the most challenging co-op I have played, in fact I would describe it as one of the lighter co-ops. That said, it is a chaotic game and players typically lose a little more than they win.
The primary challenge is balancing how far you go into the ever growing temple (new tiles are placed that make the temple sprawl out over the table) and how far you get from other players. As the review suggests but does not make clear, certain dice combos are required in order to move from room to room and players can not cooperate if they are not in the same room. So if your die get locked or you need help getting a treasure you may have to wait for another player to make it to you. Additionally, the soundtrack (you can use a cd that comes with the game or a mp3 that you can load to your phone) has a gong in it at different times during the game, after it sounds you must return to the center tile within a matter of seconds (30 I think) or you will lose one die for the rest of the game. Also, the game comes with a nice expansion that can be used to ratchet up the difficulty level.
There are also several other expansion out there for the game that add appreciated depth. The publisher Queen Games, recently kickstarted a big box version of the game that will include all of the expansions with a few, mini expansions.
The real joy of the game is the tension that is created as you try to beat the rapidly dwindling clock. Time is very tight, and you don't know when the exit will resent itself, nor when you will acquire enough gems to make your team exit (if everyone doesn't get out you all lose). I would characterize this a must have for families, a very worthwhile get for light gamers, and a I'll play if you buy it for heavy gamers.