I built mine with hydrocal. Pain in the.... need i go on.
But it works! all you need to do is be sure its level if you plan to put buildings or anything on it. In my case, so much of my layout ( being closer to the urban side of the spectrum) was pavement i just poured it down in huge areas, and and as it turns out iprobably could have flattened it better, but its all already painted.
Once laid down, you can take a hobby knife and cut all sort of lines and cracks out, and it looks good. Look at this concreat loading dock! i still need to decide the scenery around it, but as you can see, it has an aged, cracked look to it. you can take a nobby knife and add the indidividual concrete squares with a straight edge. when i get the rest of my roads done, i'll start adding the weeds we all know will erupt out of those cracks!
Its pretty messy though, and speed is important. I reccomend making smaller batches then the instructions say. I only get about half way through before it starts becomeing to set to work with.