I agree that the game is much more interesting in Hard Routing mode but I won't say it is necessarily intelligent. You might have a track layout like this (not necessarily the best design) with trains A and B heading towards each other
-----------/------\--------------
A---------/--------\------------B
---------/----------\------------
and sometimes wind up with this.
-----------/--AB--\--------------
----------/--------\-------------
---------/----------\------------
even worse you might have a layout like this
A----------\--------------------
-------------------------------B
and occasionally wind up like this.
----------A\--------------------
--------------------------------
with A just sitting there after B passed by.
The problem with routing is that I think the routing intelligence works only on the same track segments only and not globally. So if you make tracks in multiple segments it might cause some problems and for that reason I'd much rather have a specific button for making crossovers and switches rather than using the track button for everything. At least that's my impression, especially going by the last situation where laying a new track segment over an existing track segment will get the train to move again (and by the way you
can delete any track segment but the system can get a little finicky so you have to be very precise).
My overall impression of the game is mixed. I was a big fan of the earlier games like Civ, Civ2 and RT2 (don't think I ever played the original RT). When I first got RT3 I hated it but grew into it. The RT series is more complex but that doesn't necessarily make for deeper game play. It also gets heavily bogged down (in both game play and performance) and there is no easy way to fix that, especially when you are buying competitors (if I buy out a competitor in RR! I invariably hit the liquidate button).
My personal preference is to play the game like a historic "Robber Baron" rather than as a train simulator (for my money this is why I felt Rails Across America is such a great game which avoids many of the pitfalls of RT such as the huge micromanagement and performance hit in the end game but it just didn't have the epic feel of RT). I like playing RT with big sprawling maps (usually the continental US plus some of Canada and Mexico) with as many competitors as I was allowed to select. Most scenarios were very limiting in those regards and it took a while to locate maps that would allow it. But RT3's AI was somewhat feeble and never put up much of a fight.
In RR! the initial scenario maps are much smaller and there is a max of 3 competitors which is why I didn't like the game when I first loaded it. That opening trailer when you first launch the game was what I was hoping for but is not what I got. So I decided that the way for me to try and play the game is to get the full victory conditions in each scenario. In the easiest mode, this is somewhat trivial so I wanted to try and do this in the hardest mode. I noticed that there is no way to select the difficulty of the AI so I was not expecting much.
However when playing in the hardest mode the computer AI is (in my opinion) much better (although to date I've yet to see the AI initiate an auction for an industry which to me is a big omission). Whether this is because in an easy mode the AI doesn't get a chance to flex itself enough or if the AI secretly gets better in the harder modes I can't say. The maps are much smaller which puts you near a competitor almost right away and the AI will buy up your stock in an effort to force you out - something I've never seen happen in RT. Plus your competitors can directly interfere in your victory conditions.
For example in the NE scenario you need to route 50 cars of passengers directly from New York to Washington before a particular time. While playing on hard routing makes this a challenge in itself, it is difficult because at least one of your competitors will gun for NY as well and if he beats you there's problems. Just getting 50 cars of passengers isn't that easy. I was close last night - 47/50

. The game continued on as there were additional victory conditions to go for but my goal is to meet all of them so I retired and will try again tonight.
In short I like the idea that you can finish a full game (over a century) in a few hours but miss the epic feel of RT. I don't miss the tediousness of RT's end game although RR! has it's own issues there as well. I do think hard routing needs to be fixed though it's not nearly as bad as people seem to think. I'm hopeful there will be more scenarios added soon (and free - not as an expansion I have to pay for).
I think I'm going to load up Rails Across America later.