It's a bit rich to hear the opposition parties grumbling about the dangers of Scotland becoming an 'elective dictatorship' under majority SNP rule. Perhaps the Liberal Democrats might have some credibility making that claim, but certainly not Labour or the Tories - any party that believes in royal prerogative powers and a majoritarian voting system for Westminster by definition believes in elective dictatorship. That's what the Westminster system is all about, and it successfully delivers it 95% of the time.
One specific concern that is being raised relates to unicameralism - the committees are supposed to do all the work a revising chamber would do in a bicameral system, and it was never anticipated that a single-party government would have a majority in all the committees. But the reality is that in bicameral systems it's scarcely unusual for governments to have majorities in both chambers. Most obviously, every Tory government at Westminster until 1997 had the House of Lords in its back pocket thanks to the hundreds of hereditary peers. No wonder it was only ever Tories who described the previous composition of the upper chamber as an "anachronism that works".