I've really enjoyed the new dlc. That's a lot of tracks, some very good ones there. I only tried the new skill games once, and I remember liking that lights out one. The 4 Extremes are all quite challenging, definitely more so than most of the base games. I managed to get the Achievement for a Platinum in every continent, but I doubt I'll get a Diamond anywhere or get a Gold on those Extremes.
It's sad that many other aspects of the game could still be better. The Track Central interface and general support is still bad. I can't see more than 50 Favorites, and I read they now download your Favorites automatically, and of course other tracks you play, but I've also seen it mentioned there was (and probably still is) a limit to 100 there. This means I need to ration and manage this myself which is ridiculous.
They've started adding some TC tracks to the world map. It's a great thing for the builders, although it shows again what a mess the map design is. There are 3 in the main map. You don't get any rewards for playing them though.