Yes, thanks for asking, i have played and i do own A-Train, A-train 3 V9.0, Railroad Tycoon 1,2 and 3, Sid Meier’s Railroads, this, Traffic Giant, Industry Giant and probably some other as well.
Track building itself works just fine, straight tracks come automatically as there is a “snap” function built into the system. You really need to pull quite far to get it curving and that is annoying sometimes but not a major issue.
Now i think you are talking about gradients, the vertical straightness of the tracks and that is little bit different. While the system mostly works well, sometimes there is little bit issues but they are caused by the player. There is a gradient limitations which can not be exceeded and thus if you end up your track on uphil, it needs to first slope to flat before sloping down. Just like in real life. If you insist on building level track or certain constant gradient, you click on that arrow on build tool which indicates the gradient direction (or flat) and you get 2 arrows more, up and down. By clicking those you can manually adjust what happens and when you set it to level for example, it truly will create level track.
The only big annoyance is the uphill automatically created at the end of the level crossing with the road unless you pull the track slightly away from the road while building.
Double tracking is as easy as in Railroad Tycoons for example, you had to manually upgrade the track unless you built it directly to double. On this game, granted, you can’t build double track on one go, but doing it the way this game does it, is not again major flaw but rather minor inconveniece. I tend to start with single track with passing loops anyway and upgrade later on when the need is there.
Upgrade functions could be more user friendly, especially for the overhead lines and high speed track, but not again a major issue. Signals… Who cares, you can’t see them anyway so why would you even bother upgrading them? I used to upgrade to high speed by building completely new tracks and maybe straightening out few sections at the same time, so had to place new ones anyway. Now i just don’t bother with signals, they are what they are.
Station upgrades? Just build a 5 platform station if you are unsure of your future needs. Not that much more expensive to do.