I use Aperture professionally. That being said the image adjusting control you get is SO superior to iPhoto, and WAY easier to learn than photoshop. I could teach someone to use pshop in 3-5 days, I could teach someone to use Aperture in 3-5 hours. I have been using pshop since 1.0, but these days 95% of my imaging is done in Aperture (unless there are layers, type, or I have to convert to CMYK).
Also, we shoot in jpeg format due to the huge amount of images we have (around 75k, and we add another 15-20k more each year). The thought of managing the storage of those in raw boggles my mind, lol. While the raw format gives you more tonal latitude, we get exceptional results with the jpegs.
Download the trial and try it. The interface is a little more complicated than iPhoto, but easy to pick up. Also, I would highly recommend the NIK suite of plug-ins for Aperture. I have completely redone our imaging workflow around nik & aperture, and the results are awesome. I am able to recover images that would be otherwise lost if I have to, and good images soar with their use. If you want I can post some examples, but I urge you to check both out for yourself...
cheers,
michael