Some users had Touchscreen issues with the N97.
The thin flex cables (three of them) would lose proper contact/bridge.

Nokia solved this issue.
It also solved the case of the self-harming camera lens.
The backplate that didn't fit in 100%.
The softness of the tilter (made more sturdy).
Replaced the main tilter material of plastic to Aluminium.
The buggy firmware.
And anaemic RAM allowance (Nokia bumped it "up" by 10-15 MBs).

Great concept, ruined by poor Nokia execution!