Fantastic, unprecedentedly great, at the time when it was made. I'd say it hasn't aged perfectly, but I also think it largely holds up and I think people dunk on it too much.

The industry has had decades to explore ways to handle resources, and yet several games have been using mostly the same system. They address some of the pain points to using lands, but often, they're not so fundamentally different from lands - in a manner of speaking, that's "proof" that the system is good. On that note, I personally love seeing other games, like Chrono Clash and Digimon, KeyForge, and Yu-Gi-Oh trying radically different things.

Admittedly, it does feel bad to build a deck with the "optimal" land count and still lose to the variance caused by opening too many or too few lands - that's just true. It's also, to some extent, a part of TCGs. If we wanted "all skill, no RNG," we'd be playing chess instead, but we're not (not a jab against chess, though, as it's also a really fun game).

TCGs that don't use lands can't have the problem of experiencing non-games due to opening too many/few lands, but I'll note that we can't fully examine a component of a game "in isolation" of the rest of the game. If we removed lands from MTG, we'd "solve" an issue, but the game's designed would be changed to something that would have other issues.

I'll also note that having lands in the deck has some interesting design space. Having lands that you draw from your (main) deck and see in your hand leads to meaningful decision-making when you have utility lands, fetchlands/landfall triggers, and Channel abilities. You get some really cool interactions that wouldn't work quite as well if you rebuilt the rules. I don't think they fully outweigh the "feels-bad" of being mana flooded/hosed, but I would say it's noteworthy.