General neglect repairs mostly.
When I got it, it needed throttle cable, air, oil filter changes, choke handle, rear brake light switch... just expected parts that are prone to breakage.
Also required a carb rebuild and sync, degrease of engine and frame.
I also replaced the stock headlight with a JW Speaker EVO II. Incredible difference in seeing and being seen. Was a quick swap, no additional wiring or hardware required.
This particular model of the GS line was styled more like a Triumph of the day than a typical UJM. During the early 80's a lot of manufacturers had gone with either the pseudo chopper styling with bull horn handlebars, and highly tiered seats, or the standard geometry of the older UJMs with slightly higher bars, mildly tiered seats, and some form of plastic body accent behind the seat. Every bike you look at from the late 70's on, tacked some piece of plastic behind the seat. The big differentiator of this model is the beautiful styling. Lots of chrome, polished side covers and silver engine coating (in '83 they painted the cylinder heads black). Nothing behind the seat but a big brushed aluminum grab bar, and a big shiny chrome fender... nice.
As far as performance: When properly tuned, the bike works beautifully as a muscle cruiser. Great on local and busier thoroughfares, and gobs of power to pass most anything you need to. Above 5K it pulls like a freight train, and below it's a quiet, comfortable gentleman's motorcycle. Stock exhaust is muted yet offers a great typical inline 4 "vroom". You won't be waking the neighbors with this bike. If you need more noise, then 4 into 1 exhausts are easily available, but will require carb re-jetting to work.
I needed to trim the seat down to accommodate my 32" inseam. When doing that I installed a gel square, memory foam, and vapor block layer. The height of the stock seat is mostly due to the fair amount of clearance of the suspension. The bike is softly sprung, but not so much that you can't enjoy the twisties. With the shocks set properly, and the stock seat, it's an all day rider.
If the bike is maintained properly (typical requirements: valve adjustments, carbs clean and synced, filters and fluids changed as manufacturer outlines) then the bike will provide 10's of thousands of trouble free miles. Mine is 35 years old and I hear "beautiful bike" virtually every time I ride it.
So, if you find a well maintained version, grab it. They can usually be had under 2 grand. The "T" versions of the GS750 are somewhat rare, as they were only produced in the US from '82 to '83, (with the '82 being the prettier of them, but that's my opinion). If you find one with all the parts, usually a good going thru will make it a great daily runner.