I think the option to specialise is a definite plus.
Once you can do the basics you can then choose to focus on offices, shops, factory installation, factory maintenance, commercial maintenance, marine (recreational, industrial or defence), aviation, rail, highways, or indeed house bashing.
I don't know about 'access all areas' (the guy who was somewhere to do a specific job but took it upon himself to have a nosey around and start quoting for stuff which was none of his business springs to mind) but you definitely get to work in some interesting places - places you wouldn't otherwise get to see.