GEL-NIMBUS 28 should feel soft, but it still needs to sit properly on your foot. The cushioning can only do its job if the heel feels settled and the upper holds comfortably through the run.
GAIT analysis can help check whether this neutral cushioned shoe suits the way you move. If you tend to land through the heel, the PureGEL® setup may be useful, but fit and stride still need to be looked at together.
The team at Smiths can also help compare size and width options. That matters with a shoe like GEL-NIMBUS 28, especially if you are choosing between a standard fit and a wider option.
Bring in your current runners if you have them. Seeing what you already wear often makes it easier to decide whether GEL-NIMBUS 28 is the right next step.