Having seen both sides for the fence I have to agree with the general consensus on the suitability of helicopter seats.
The worst seat I have yet experienced was the one on the Bell 47, but I guess lower tech than a shelf with a flat foam cushion one is hard to achieve. I think though that this was indicative of how designers regarded crew comfort. The constraints of weight are particularly difficult for designers to resolve, but there have been plenty of great suggestions on this thread which do not add excessive weight.
As some one said previously, the original 'Tiger' seat was particularly dreadful and I seem to recollect that it was akin to perching on the edge of a shelf. The later seat was a real improvement, but the ability for it to recline was a particular waste of time simply beacuse there was not enough space in the flightdeck to actually do this. The arm rests were probably the best point together with the longer leg support and the gel seat insert (as long as the gingerbeers hadn't substituted a block of foam when the gel sac leaked)
The stretched red nylon shopping bag on the Bell 212 should not have been allowed under any circumstances.
Now I am experiencing the difference with an Airbus 330/340 and while the improvement is huge, there are still difficulties in creating a truly comfortable seat, even now we are actively trying to develop a more comfortable cushion, though the scope for adjustment is so much more than that available to a helicopter designer and everything is made so much more solidly.
I would have to agree with Nick in only one minor point - it is difficult to create a seating arrangement which satisfies all pilots, however the notion that what we have is adequate is seriously optimistic.