The fundamentals behind iTrain are keep it simple, make it affordable and run on any decent computer. Many people have heard that you can control your model railroad with a computer, but that the learning curve is very steep and the fun is gone after everything runs automatically. With iTrain the learning curve is less steep, because you don't have to program to get things done. You just inform the program what your layout looks like. Also combining manual control with automatic control is easy.
The single most important thing is to divide your layout in blocks (just as in reality). Then you define how the blocks are interconnected (via which turnouts) and which feedbacks and signals are attached to the blocks. That is enough for automatic block control. This is some work, but then automatic control is also at your fingertips. Setting up a train route is as easy as selecting the order of the blocks and specifying wait times per block.
You don't have to control all your locs automatically. You can fully control a loc with the mouse or the keyboard. You do not need to buy extra or remote controllers, but just a wireless keyboard or mouse that you may already own. Also specifying the speed directly by using the numbers 0-9 for speed 0-90 km/h (and 100-190 km/h with the shift key) is a delight.
Switching turnouts via a red or green button is not very intuitive. Clicking on a drawing of your layout is. This is called a switchboard. Also multiple turnouts and signals can be switched via one click in the switchboard by creating a track route.
In your layout every element has a number or address. In iTrain everything has a name and iTrain will make the translation between the name and the address internally. You can work with the names (and names can also be numbers, but may be combined with letters) that are independent of changes in the wiring. For example changing the address of a turnout must be changed in the turnout, but all other elements like blocks and routes are not affected. This keeps maintenance costs and time low.
Loc functions also have a name and no function number that needs to be remembered. If in a certain block you need the flood lights to go on, for any train that supports it, that is setting one function in the block. No programming with f1 for loc 1 and f2 for loc 2, etc. Also for new locs it works without modification. Keyboard shortcut for loc functions are a letter and are independent of the F number.
iTrain imports the objects on the ECoS and Central station and keeps them synchronized so that starting with these systems is even easier, because you do not have to define your locs, turnouts and signals anymore.
iTrain has no limitations in size of the switchboard or the numbers of locs it can control. All limitations are depending on the digital system used. Large layouts do not take up significantly more processing power, because no computer power is wasted by calculating everything so many times a second. iTrain is event based internally so that only changes will trigger recalculation of that part that is involved.