I've found a few things with using PocketHAL for Symbian that I'd like to share:
1) When running the PocketHAL included examples in the debug Symbian emulator, a memory leak warning will be displayed on exit. This happens because the STDLIB is used, which allocates memory buffers for itself, which must be freed on exit. To make the warning go away, simply add the following to the end of GameBase::~GameBase() :
CloseSTDLIB();
2) On Nokia N70 devices, when loosing focus and then returning to the application the screen will be messed up, displaying at a quarter size of the screen and with a lot of greenish garbage pixels. Appears to be a PocketHAL issue with these devices - a workaround is destroying the Display object when loosing focus (OnSuspend) and creating it again on gaining focus (OnResume), which will work fine.
3) Always do Display->Swap if you call Display->BeginScene. For some scenarios it might make sense to quit halfway before calling Display->Swap, for example if you discovered that nothing changed and no swap is needed. Failing to do so will work fine on older Symbian 6.1 and 7.0 devices but will introduce undesirable effects on Symbian 8.0 devices (for example Nokia 6680) like machine reboots when exiting the game.
Regards,
Jorge Diogo