I'm partly exited about this game because it expands all the way up to 8 players. Very curious to how the game experience shapes according to the number of players.
With 2 players the game works well for the same reasons that 1860 does. In some respects I think it probably works better because of the random setup - you're always playing a different game. There aren't as many shenanigans you can play with towards the end of the game, but you get a lot more options with the larger number (and variability) of companies. In that sense it can be more bewlidering unless you play the first few games with the same company setup, just so you can work out the dynamics without having to worry about the relative strengths of companies.
3 players is "fairly" friendly, but do be warned that the level of control you have means that good play can make for some amaxing moves. I've been on the receiving end of an opponent buying his way through the first 5 permanent trains in consecutive operating turns, rusting pretty much every train held by his opponents. Needless to say he won by an landslide. With more players you're unlikely to end up with enough control to pull off moves like that.
4 players is probably the "nasty" game. The starting money allows you to float 2 initial companies, and if everyone does that there simply won't be anough trains to go around - 7 'A' trains, and 6 'B' trains, and the 'C' trains rust the 'A's!! The 4-player game is the reason why A-trains and D-trains come with a free warranty.
5-7 player games are much friendlier as you'll only have 5-7 companies starting, so the initial pressure isn't going to be as bad as with 4. With 5-6 players you'll be going through 1 or 2 company mergers per player. With 7 you might struggle to make the second.
8 players is getting back into the realms of being a tough game, for the same reasons as the 4-handed game. It's probably prodent to pass on starting a 1st-round company if you can't get a half-decent one. But that depends on which companies are in play, and which ones will become available after the first load of operations...
I know this might not make a lot of sense unless you have an idea of how it plays, but hopefully it will give a taste of what people can expect from the game.