I've had buddies on 690's since they first came out, and had years to check them out very carefully. My only previous KTM, a 1983 495, was an abysmal money-pit.
The 690 has a good engine, but due to it's high performance, could just never last like an XT600 for instance. 690 clutch is also something to keep an eye on, and cannot take nearly the abuse the Japanese wet clutches can. Several of my friends had clutch packs destroyed.
The frame and suspension is very good.
The tank in the arse is great fun, especially when you have to unpack to fill up. The speedo cluster is the worst I have ever seen, it is only possible to read speed, etc in certain
conditions of light, and of course at night with illumination.
Note that I am referring to the speedo's on the non-revcounter models.
I have been on several trips with 600kms+ days, and the 690 is really not that uncomfortable, once again not as comfy as my XT600, but then it is a racer compared to the XT.
I have gotten 25.5km/lt while accompanying cyclists on a long one-day event, and even at mixd riding, fast and normal, it gives around 18km/lt. This is great.