Hi DrummerBen!
Assembling the Zongshen gs250 Sportbike was pretty simple, the front wheel needed to be bolted on, and I think the rear rack/passenger grab bars need to be bolted on.
The hardest part of the assembly was holding the front off the ground to get the wheel set in between the brake pads. I ended up having my brother lift the front end while I slipped a Home Depot bucket under the muffler/engine cover. There is no center stand on this bike, unfortunately.
I have put on about 200 miles, and the bike runs very well. I have managed an actual top speed of about 70mph according to the speedometer. It gets to 65mph very easily, but past that it accelerates very slowly, and at wide open throttle.
I have tuned the bike a little to my comfort specs, out of the box, the clutch did not engage until the lever was almost all the way out, making it hard to feather the clutch in tight turns, so I adjusted that on the lower adjusting screws by the engine.
I also forgot, be careful taking the side cover off to access the battery, I believe that there are 3 screws that need to be taken off for the entire side cover to release, I only took off 2 and tried to bend the plastic, and ended up breaking the back plastic bracket.
Are you new to riding, and/or is this your first bike? I think that for the price it is a pretty decent bike.
Good luck, and have fun with the new bike!