I've never played Magic: The Gathering, and haven't the first clue about the lore.
That said, the setting sounds intriguing at the very least, and potentially very interesting. A hyper-urban setting, with lots of factions, and seemingly a bit of a Steampunk vibe? I'm pretty much sold based upon the general description and cover alone.
I'm very glad that Eberron's getting some love, as it's a favourite setting of mine, but even before that announcement, when people were speculating that Ravnica was going to be the only major setting release, I still found it an interesting concept, and was looking forward to exploring it.
Ultimately, if WotC can pick up this big chunk of developed lore that they have effectively just sitting there, and use it to deliver a fully fleshed-out setting that is effectively new and unseen to most D&D players, that's an economy of resources that I can respect - and if the finished product is a setting I can use and enjoy, where exactly is the downside?