i haven't really had any problems. InstallShield really just uses the MSI interface. it provides additional features for convenience, but the most important thing is that it fully supports the MSI interface. since it supports MSI versions 1.1-3.1, there is no reason why an installation built with IS would be unable to run on any machine with some version of MSI on it.
i'll update you if i run into something quirky, but so far, no prob.
