DOM is a great tool for many markets... FX just isn't one of them.
It would be useful for FX traders who want to know if their large sized orders would be slipped when marketing them. Since I'm not punting $1+mm per ticket just (yet..ahah) it's not on my radar.
I pretty much live out of my DOM and Time and Sales windows with equities at work... but in FX, I don't really bother looking at the DOM.
I have heard that some people get value from watching currency futures on the DOM with a time and sales feed on the side.. kinda like a proxy to the rest of the currency market, but I've never stuck with it long enough myself to determine if it's valuable to me.
That said, most of my scalping these days has been event driven...but not all.