My two most recent boatyard experiences were both positive.
First, an exhaust repair, where I was given an estimate and dates. The work was done at the agreed time and I was actually billed less than the estimate as some of the existing parts were good to be reused.
Second, some significant steelwork mods - windows plated up, new portholes - modified roof handrails... new solar panels and a complete repaint. All done to time and estimate, even when I threw in a curve ball by choosing to buy new window units rather than reuse the existing ones.
I have to say that in the second case, I virtually had to drag the guy out to come and look at the boat to see what I wanted doing because he was originally only willing to give ballpark quotes based on boat length and a general description of the work. Once we were over that hurdle, everything went smoothly.