A lot has been said already, so I'll just add a couple of things that I noticed in other comment.
There was a mention of gear indicator showing "1" when it's in neutral - that's a bad gear position sensor, it's going. It looks like a fairly common issue, I replaced mine a bit ago.
The valve clearance check/adjustment is at every 15k miles, which costs between $1500 and $2000 typically at a dealer. You can do it yourself, of course, it's not that difficult, it's just a lot involved. Other regular maintenance is at every 7500 miles, the oil change and that bit, costs about $500 at a dealer.
OEM tires don't last all that long, I go through every 4-5000 miles. I recently got kind of fed up with Pirelli and went with Michelin, and far happier with it on the road.
Other fairly common issues - hot starting (just remove the EVAP canister), exhaust flapper servo motor (if you ride in rain, the cable will eventually seize, just remove the motor and cable), weeping oil from head gasket, the stock seat is a total rubbish if you want to put (a few) miles on, but there are aftermarket stuff available.
General reliability? It's good. 899 is my first Ducati, and I was really hesitant, but the bike has been rock solid. Is it as good as Japanese counterpart? I don't quite think so in the long run, like 30 years, but it's as good so far. The service is expensive, but you can save a bit by doing majority of it yourself, you know, like simple things like oil/fluid change.
And if it makes you feel more confident, there is a member here who had 899 with something crazy like 75k miles on it before it got totaled.