Putting my differences with the system in place aside, I have to admit I think it's pretty accurate just by looking at the top 25 or so players.
I see a lot of names that were also on top on the Iso leaderboard, so if you're a good player, you'll get an appropriate high rating in the end.
I'm even proud that I'm in the top 25 (~6200) given how little games I play, maybe 5 per day maximum, so it seems with this rating system there is less focus on uncertainty. And I don't even have any cards, full-leech-mode!
What I take away from it is this: I think I can hold my own and play competitively against anyone on the list and that's all that matters for me. I don't need to be on top, but I like to be good enough that I don't feel overwhelmed by anybody up there. It's a bit sad though that there are many kingdoms with blatant dominant strategies or, more likely, sub-strategies like: be the first to get or do X, making shuffle luck a big factor in those games. However, the randomness is also a feature, making it able to pull of some crazy comebacks.
I don't know how 4ks and 5ks feel about the system though.