Once you get past the nostalgia factor, this episode is unremarkable. You have a potentially interesting scifi concept that's completely wasted (the Dyson Sphere) and a visit by a fun 2nd-tier original series character that is executed in a completely predictable manner.
I say predictable because Scotty does exactly what you would expect from a "relic" - he complains about the future, bickers with Geordi (their catfights are annoying) and gets drunk on the holodeck. The first time I saw this, I was extremely disappointed.
That said, once you get past the disappointment at a wasted opportunity, this is not a bad episode. James Doohan is clearly having a lot of fun uttering the canned but nevertheless amusing lines fed to him by the writers. "Synthetic alcohol, synthetic commanders!"