I think its important to preserve constituencies in some manner, because a party can be fairly popular but not its senior figures, who would then be protected under pure PR. The sensible thing to do is to switch to a system of voting that still has (redrawn) constituencies, but in which voters can express preferences rather than having to commit all their support to one candidate. How the system deals with these preferences can vary, but if they are there then the full nuances of a voter choice can be at least more completely considered, as opposed to being hidden under a single "X" next to a single name or party.
Even with these subtleties captured it might not change the vote much. In a huge number of Scottish seats nothing would have stopped the SNP. Perhaps that's a good thing; as it is, while the overall Scottish result is disproportionate it's also true that none of the main parties fared well at all. In a pure PR system Labour would still have held 14 seats. That's probably about 10 more than they should have got last night.
A better electoral system should be more proportional, but not exactly so.