If you're running a Spelljammer campaign, it doesn't strike me as a bad book. There's a number of interesting worlds that could work for places to land in a game. But it frequently shows up the problem of any space SF or space fantasy setting; you get many interesting planets that could be every bit as productive as Oerth or Toril, and you get detail for three pages, which makes each of these settings is in practice very tiny. There's a ring planet (borrowed from Niven, of course) that has a 100,000 times as much land area as Toril. You could stuff every fantasy world ever printed onto this outside space fantasy on to this world, and have enough space to justify their differences. If what you want is 15 distinct new planets, with a good helping of fire, air, water and weird planets, it does that fairly well, I suppose.