My previous car was an Altima 3.5SE with a CVT. It was indeed incredibly smooth and it was great to basically have an infinite number of gears so you could always get the exact amount of acceleration that you needed. It also had a manual mode which basically was set with certain gear ratios for the 'gears'.
That said, power delivery left something to be desired. If floored, you don't get that burst of power from a downshift but a gradual swell of power until youre at redline.
When I got the 135 I realized how much I missed the actual sound of the engine hitting redline and then dropping down for another go at it (Even if I do have an AT).