In my view the case for Scottish independence is a strong one. The borders of Scotland are clear and undisputed; the question of who will be Scottish presents no problem: i.e. anyone who lives in Scotland and who wants to be. Unlike Ireland, there are no politically significant ethnic differences in Scotland complicating independence Unlike Wales, Scotland possesses a geographical heart, its Lowlands, which is geographically distinct from England. Scotland already has semi-autonomous status in the UK and its separate cultural nationhood to draw upon.
Other structural factors push Scotland towards independence. Britain isn’t a federation (Cf. Quebec in Canada) and an English/Scottish federation (with Wales and Northern Ireland fitted in somehow) is a non-starter given the difference in size and power of its would-be constituents. In any event federations of two don’t make successful marriages (Cf. the former Czecho-Slovakia).
Future developments in London might favour independence. This year Cameron’s Tories will probably triumph in England, but not in Scotland. The decomposing glue of Britain’s unified Labour Party sticking together Westminster and Holyrood will further come unstuck. Scotland will want to make its own choices in the world, and so it should.