I've enjoyed my ST1300 but I'm not wedded to it.
It's never left me stranded and the engine is fantastic. Don't think there's a better touring engine available. Once I upgraded the suspension (front and rear), it handles great, real solid in high speed sweepers. Plenty of room to carry junk for trips. Great wind/water protection.
Maintenance, well let's just say I've had my issues with brakes, coolant leakage, final drive bearings, now an intermittent electrical failure (electrical qualified by being almost 9 years old; IE expected). I expect rubber components to start failing next because of age. Just more maintenance than I want to perform.
I found fault with the stock setup. For me, the seat was terrible. The suspension was set up for folks weighing less than 185 lbs and was terrible for anyone weighing 200 or more. The mechanical linked braking system was overly complex for simple maintenance, many pages have been written in this forum on how to maintain them thankfully. The shop actually messed mine up. The water hoses are weakly secured which caused my bike to leak like a sieve when in freezing conditions, fixed with torque-able clamps. The final drive bearings are weak for the load they are driving, I replaced them with a set of needle bearings from CBR (CBX ?, don't remember, you can find the source within this forum).
If I can't get my electrical issue fixed by March I'll bite the bullet and spend money for a new bike with cruise control and lower center of gravity and hopefully lighter. Thinking of the R1200RT. I'll also require a better suspension setup, don't want to have to upgrade that. Not sure it's possible to get a really good seat on a new bike since everyone's butt is different. Not going to miss another riding season due to my inability to keep up with age related issues, yeah I missed every long ride I planned last year. I got distracted by the electrical issue and low sided the bike, my fault but it wouldn't have happened if I wasn't messing with the Garmin. After I got the wreak fixed, my front SMC failed causing me to miss another LD ride. And my electrical issue remains.
If you enjoy working on machines or have enough money to pay someone to do it as it ages, the ST is a fantastic touring machine. If I were a belter mechanic I wouldn't be considering a new bike.