I find him very interesting to watch. His game lacks variety in the conventional sense, but there's plenty variety if you're willing to draw the lines a little differently. Maybe his game is "monotonous", but it's an avant-garde monotony.
Although his net game is p*ss poor, I don't think coming to net is inherently interesting. Medvedev's one of the few players who routinely takes a midcourt ball and immediately retreats to the baseline instead of coming to net. To me that's novel and interesting. Maybe it's not optimal, but it's interesting. I also don't agree that he doesn't vary pace. IMO one of the things that makes him so effective is his knack for suddenly injecting pace and changing direction when his opponent doesn't expect him to. He generates his offense from neutral positions via his opponents' expectation of continued neutrality. To me that's every bit as compelling as a player who generates offense with raw pace or early directional changes.
I also just think his play style is really interesting given his height. He's a player who lacks the requisite technical ability to excel by playing in a manner typical of a 6'6" player, but he's compensated for his technical deficiencies by constructing a play style that only works because he's unusually fast and agile for his height. He became a top-3 return game player on tour by hitting flat from a deep return position. He doesn't play like a 6'6" player but he serves like one. He has perhaps the most unpredictable second serve in the sport outside of Kyrgios and Bublik. He can't volley and looks awkward coming to net, but he's somehow excellent at retrieving drop shots. His backhand has a unique side spin that keeps opponents pinned to their backhand corner in CC exchanges. He rarely errs from neutral positions, so most points he plays are highly competitive.
There's much more I can say, but one more thing that fascinates me about Medvedev's game is the tension that exists between his preference for grueling, extended rallies, and the fact that he doesn't possess superhuman stamina. Medvedev has little reason to be confident that he can play his style of tennis indefinitely without hitting a wall. He simply goes into every match betting his opponent will hit the wall first. He's usually right.
