A long, long time ago I played Railroad Tycoon, on a positively ancient Mac, and loved it. Sid Meyer has a knack for creating great games (Pirates! was another one I sank more time in than I care to admit. And then ther was Civilization...), and RRT was great. It's a real-time railroad AND business simulator (the latter part is what makes the game so interesting for people who yawn when looking at model rail roads)
Fast forward to a few days ago when I became aware that there now is a simlar game: Sid Meyer's Railroads... Curiosity got the better of me, and I purchased it. Well... I'm not exactly disappointed - but neither am I ecstatic. I've (already) spent a lot of time playing it, and it is definitely worth it if you, for exaple, compare that to what you'd get out of a cinema ticket.
The graphics are nire - really nice. The music is ok, and can be turned off (not eveyone likes period-realistic music, and a banyo positively grates on my nerves). The interface is a typical windows port that takes getting used to (to be honest though, the same was true for Railroad Tycoon).
The biggest problem, though, is AI, or more specifically, train routing AI. Never, ever, in a game should you design your track with a loop in it. The AI will invariably start routing your trains to never-never-land, running a LA-San Diego train through Utah, completely killing any profit, and - if you don't detect this soon enough - may even bankrupt your RR company (remember - a RR AND business simulator...). The problem here is of course that a circular track is one of the most efficient designs for many problems...
Another problem is with track laying - very soon after you start your first little route, you'll need to double-lay tracks to avoid dead-locks. Unfortunately, the way RR implements the UI for double-laying is so incredibly stupidly designed, that you'd end up laying unconnected (but connected-looking) tracks more often than not. Now couple incorrectly connected double-tracks with an AI that has gone off the deep end, and you end up with a very, very unpleasant - if not frustrating - gaming experience.
Multi-player is new for me, and so far I felt I'm not up to it, so I only played against the computer. Since computer players never make a mistake laying tracks, they will wipe the floor with you for the first few times.
Re-playabilit of RR is high because you can randomize terrain and tweak win conditions (like in CIV).
So, if you are prepared to put up with these annoyances - or if you simply love railroads (RR can be run in a 'Sandbox' mode where you can play completely unrestricted), RR will give you (or rather take from you) hours upon hours of fun.