I have never managed to get the BBC download to work. I have and use Final Draft and it is possible to talor the templates to come somewhere near what you want in most instances.
I started out writing feature length film scripts and this is where a formatting programme really comes into its own. There used to be an insistence, although I believe less so now, that where a piece of dialogue was split between pages you needed to write (more) at the foot of one page and (con't) at the top of the next. This is an absolute pain if you have to do it by hand as every time you edit a line out, you have to go and re do any page that comes after it. Which can be over a hundred or so.
Having the character name pop up intuitivly is another thing that assists me in scenes where there are two people speaking in single words or short sentences.
I used to use a programme called ScriptWare (i think) this was better than final draft in my view, but is no longer available.
I have written in Word and would certainly choose Final Draft over this but, as has been said already, it's the actual words you write that count. I find with formatting software, I spend more productive time in each session.
And I found Marc Blakes crit very useful and would urge anyone to invest that amount in themselves. I wouldn't give that much feedback for 60 quid and I don't know what I'm talking about. O, not with regard to Final Draft, I do have experience there.