Depends on what you consider major problems. I can think of more than two people who got bogged-down trying to work around similar issues, and a lot of things that they might have otherwise achieved.

Doubling is gone afaik. Of course you can software scale, but every bit of waste adds up. A 2x scaler means you must copy 4x the data. I'm not too worried about getting some decent/simple screen updating, but I am concerned that the apps that need to go that route will end up necessarily breaking the windowmanager concept - bastard OS stepchildren swept out in front of the doorstep.

I'm wandering a bit here but i hope this bit is interesting: one of the advantages of the maemo5 compositing task-switch/fullscreen metaphor is it's even more agnostic to historic linux programs. Managing those apps as fullscreen units means less putzing with layout changes for the smaller screen. In other words the new taskswitcher helps visually integrate those non-native (e.g. SDL) apps with the rest. But what's the point of havin an overview of your *running* programs when the game window is either black, or boggin down your scrolly-overview with 15fps updates?

These are the things I wonder about.

[edit] while i'm goin..

How about allowing for badly ported things or apps requiring higher resolution to expand the desktop to higher (and/or higher/wider) than 800x480. User would have to pan around desktop with stylus+key combo, or possibly by tilting unit around. Hey as long as we are doing Gl...

https://gforge.ti.com/gf/project/dmai/ This might be an alternative - daVinci multimedia application interface.