I've been a trainz user for years, there is simply nothing else like it, especially on the mac platform.
Although it's "version 1" for the mac, don't let that stop you, it's actually based off the same code the PC version is, which has had about 10 years of updates.
Speaking of Updates, If you take the extra step of setting up a profile on the vendor's site (there's a button to help you do this when you run the game) the game will give you to pull content updates. Trainz has always been a community game - meaning that thousands of enthusiasts from around the world have made things like buildings, trees, trains etc. Much of this content is included in the game, and even more is available online on the "download station".
So again, although it's a "Version 1" product, there are in fact updates to the content and this is a mature and stable platform.
Easily worth the money for something so unique.
That said, Trainz can be easy or hard - it depends on how much you want to get into it.
Do you want to control a train on a few different layouts? that's easy.
Do you want to create a layout, that'll take some effort, and some understanding of a few things. it's not impossible, but you will have to think and use your head.
Do you want to download new layouts, cars and buildings from the internet - that's easy, but not well documented at this point.
So my review reflects that in its ease of use score...