Great to have a variant map! For 4-6 players the original is still my fav (love the 'open' feel, the need for bigger trains, and the arc of the game), but this map is the go-to for 2-3 players (no requirement to battle for the NE, more chances for interaction among all players), and good to use for a change with more players.
The games ends quicker, so less need to upgrade. There's a decison to make of when to 'go across the mountains' and seek more cubes, but it's not as drastic as the in RRT. The costs of building and the special cards encourage shiping smaller runs, but I think it's still worth it to build a 3-train as fast as possible. The Major Lines are now a fix entity on the board, which makes them more fair but not as fun: I liked the tension in their randomness in the earlier game. The map seems more balanced with some outlying towns that may/may-not see action, but nothing like the wasted SW land in RRT. All in all, I'm happy with my purchace.
Played prototype. Very enjoyable stock market addition. Think I like it even better than the base game. Comment vs. 18xx? I'm not at all a 18xx fan. I find those games to be slow and a chore to play, but I found Barons to be dynamic and fun.