Here are sample crops from an outdoor scene at each of the Canon Powershot S90's ISO settings. Next to each of these crops, there is a crop from the Fuji Finepix F200 EXR at the same ISO setting. This is the flagship Fuji ultra-compact which currently produces the best image quality of any fixed lens camera. Both these have manual controls and stabilized wide-angle lenses.

Images below are all unmodified 100% crops from their respective cameras. Only the ISO sensitivity was set, the remaining settings were left on automatic or on their default values.

These crops help determine which ISO settings can be acceptably used on these cameras. As noise increases, most cameras compensate with noise reduction which introduces softness. The result is that, while you can partly reduce noise at the expense of details, the maximum acceptable print size gets smaller as ISO is increased. The point at which a print become unacceptably noisy is a matter of personal taste.