Broadly speaking, it's quite true that the subjunctive is widely used in modern Romance languages. As far as I know, all languages having a verbal mood that is called "the subjunctive" use it for roughly the same, except for those languages with optative mood besides subjunctive. Frankly, I think there is little to say about the subjunctive in Spanish that can't be applied to that of all the Romance languages. A fact I remember is that the future subjunctive is currently used in both conversational and written Portuguese, while in Spanish it's hardly ever used, not even in the modern written language: it's only found in a few fossilized fixed expressions, in literature (specially that from the 19th century and before) , in legalese and in purposely archaic speech.
You must take into account as well that there's some conflation between the imperative and the subjunctive in all instances but the affirmative second person (tú and vosotros) imperative.
In all other cases (negative imperatives with tú and vosotros, imperatives with usted and ustedes, first person plural imperative and third person imperatives) the forms used are those of the subjunctive. But keep in mind third person imperative is an old-fashioned construction used only in fixed expressions and legalese, and is often not even recognized as an imperative form by most speakers. Examples can be found on the Lord's Prayer:
Padre nuestro que estás en los cielos
Santificado SEA tu nombre
VENGA a nosotros tu reino
HÁGASE tu voluntad...