They are great bikes, I did almost 100,000 miles on my '03 bike.
The headlights are poor if you ride at night, especially if it's wet. Upgrade to HID's for both units but don't fit the ballasts in the instrument pod as it plays havoc with the LCD rider info display. I fitted one either side of the headstock under the front of the tank. Perfect. You can get top quality kit from Les Wassall on this forum. (This was the first mod I did to my current bike as well.
I dumped the rear can and fitted a stubby tail pipe. Search stubby on the forum. Saves about 6½kgs in weight and means that you can use a full size left pannier without an exhaust recess. It also makes the bike a bit more flexible at low speeds and improves fuel economy a little. A bit crisper sound but not really much extra noise. This only applies if you have the original catalyst in place below the gearbox.
I removed the servo abs system before it could be a problem. You end up with better brakes (more feel and less grabby), it can cost nothing and you reduce the weight by another 7 or 8kgs. On the subject of brakes, the hoses are probably original, change them for braided ones. Even though the mileage is low they are old and may be deteriorating. It's usually the inner layer that fails and causes a blockage whilst the outside looks fine.
Wilbers or Ohlins suspension at both ends make a great bike even better.
I used Tobinators with the standard screen but it was never great. At its best it wasn't as good as the standard screen on the Super Tenere that I now have. If I'd kept it I would have fitted a
Calsci screen
Change the final drive oil every 6,000 miles when you do the engine oil and filter. It takes a just a few hundred mls of oil and a couple of crush washers and gives you early warning of any FD issues, it is one of the few weak points on the 1150.
Ride, lots, enjoy.