ZoomIn is an excellent Upload-Store-Print service. They have grown really fast because of their good customer service, easy to select gift items, good user interface, and attractive marketing techniques - the 25 -30 free prints(only 6x4) that you get. No wonder why it got The Best Photo Sharing Site - in the PC World Best of the Web Awards.
I recently came to knwo that ZoomIn can also be integrated with your iphone, even though I have not tried it(Oops, I dont have an iphone!)
I liked the Crop feature available when you order a print. An ofcourse, I missed one thing - the metallic prints - A new dimension to your photos(May not be suited for all photos, though).
And others features like organising your pictues among your albums, tagging for photos, albums, etc are defenitely there.
The email upload is a powerful and handy tool, which enables you to upload the photos to a dynamic secret emailID, the email address itself has a secret code. ie, yourID_@zoomin.com.