Depends on the quality of the assembled and stiched panorama. If you gave a 4s to experienced pano photographer with a suitable mount, they would be able to make acceptable panoramas in many situations (if it didn't stress the sensor too much, e.g. low light or extreme contrast). The pixel density (pixels per radian) should be sufficient to meet the minumum spherical panorama dimension, and with careful shooting you could get sufficient quality source photos. But it wouldn't be a great choice to use if the intent was to make good quality panoramas, especially for inexperienced photographers.
What do you want to do? Why use a 4s? To do panos properly, you'd want to use a tripod and panohead (it is possible to do it handheld but it's quite tricky to get good results this way) so you might as well use a more suitable camera as well.