Much as I dislike the restrictions, one thing that cam be said about the Apple app store is that all if the apps have been 'approved'. They may still be crap, but they should be malware free, unlike some Android apps, so it would seem.
In complete contradiction to the above, I've just jailbroken my iPhone, simply to change some of the alert sounds to ones I can hear. Still got my eye on a Desire HD, though.