looks fine to me. nothing groundbreaking but still cool concept kinda like modified incursion/delve, and more crafting is always fun.
let's be fair it's not that easy to produce a fully fledged league every 3 months, come up with brand new stuff every time. they have done an excellent job so far. in fact I think this is not very sustainable in the long term(remember how we used to have different leagues for SC and HC? sure one reason they changed that was so everybody could experience the league and not miss out, but also that they didn't have to produce TWO different leagues per cycle), so I predict that in the end things will be further simplified to basically new league new season but not much new stuff or not necessarily league-specific content. on that note, private leagues also seems like a win-win for all, you get to spend some coins on it, and ppl seem to enjoy these private races(watch or participate), especially if you're bored late-league. I suspect there will be some major changes coming in regards to leagues when 4.0.0 hits (next year I guess).
also remember, this is the first league of the year, there's 3 more coming later on, so, plenty of new stuff to look forward to. I hear melee re-balance in 3.7 (June).