Remember that only trips that go wrong get remarked upon here, the vast majority happen absolutely fine and there's no reason to write about them. I've been using the service regularly since March and the worst that's happened is the destination being moved from Glasgow to Edinburgh twice which is a minor inconvenience at most.
I think this is a really important point, and worth repeating every so often for the benefit of anybody viewing the thread pondering a journey.
I took my family to Scotland this August on the sleeper, up to FTW, back from INV. Monitoring this thread filled me with trepidation, but our journey was very good.
On the day, I told my wife we were some of the lucky ones. But on reflection, I get the impression it's more accurate to say that we weren't some of the unlucky ones, who are relatively few in number. I'd skewed my perspective by only reading about bad journeys, when the majority run smoothly.
Don't get me wrong - I'd still swap it for the old Scotrail set-up in a heartbeat to get the £19 bargain berths back