IMHO, it was a really good basic design that suffered from a lack of development. Lovely cockpit with good ergonomics, BUT the Integrated Instrument Display System had a habit of progressively-disrupting the display (as mentioned earlier, no spares available) and the seats/cockpit doors were definitely part of the weight-reduction 'programme' that the design underwent before entering service. The manufacturers definitely allowed a pilot to participate in designing the front-end, as things were simple and unambiguous - unlike the EC135, its main competitor, which still features design nightmares that should never have been allowed to leave the drawing board.
NOTAR had its own peculiarities - unlike a wholly-mechanical yaw control device, things like air density meant that a given pedal input had a different effect from one occasion to the next. It was the only aircraft I have ever operated where you could overtorque the beast just by putting a large pedal input on the ground. Curious cross-wind limits made operating in the police role a challenge, but as an air ambo/ HEMS machine it was another - much better - story. The cuboid cabin, although isolated from the cockpit, made life for the medical crew very straightforward, unlike the tapering shape of that in the 135. Access with the tilting stretcher was comparable to that of its main competitor. Where the aircraft really shone, though, was the way it interacted with the area around the landing site and with the people you get near a HEMS scene. She was quiet in flight - none of the interference twixt MR downwash and TR vortices - and as has already been mentioned there were no hazards to life or limb aft of the cabin. Anyone standing near the dustbin or the Coanda slots would just get a waft of ambient-temperature air in their face, as opposed to encountering a fenestron that will take yer fingers off at the elbow or - worse still - a tail rotor with all the associated hazards. The MR remained above the height of even the tallest Trumpton-with-his-hat-on, which helped when they decided not to duck on entering the disc while helping to carry the stretcher. Everyone's IQ drops by about 50 when they encounter a heli turning-and-burning for the first time, so it was really helpful to know that they were less likely to damage themselves around the 902. Mind you, you could get something worse than a paper-cut if you ran your hand over one of the vortex-generators they added to the tail-boom after the stretch mod... made cleaning the aircraft a right pain, as they used to shred the sponge or cloth.
It was the peculiarities of the aircraft's early history that did for it - the very-odd deal with the Dutch Police, the acquisition of the manufacturing company by people with a fascinating background (selling submarines and Leopard 2 tanks to Chile? some fact-checking required)... there was no investment, just when the design really needed the bugs sorting out and implementing the improvements that had been identified as necessary when the aircraft first entered service. The autopilot was never as good as that in the 135, and the rotor mast design which was probably ideal for New Mexico wasn't really up to the demands of the European weather systems. Mainly, though, it was the way contractors, sub-contractors and employees were treated (Kaman nearly went bust as they were owed so much for - I think - the MRBs) that led to the dead-end for the 902. A great shame.