I usually don't order from other merchants that sell on amazon, it's just too much of a hassle (plus the shipping is more expensive). I order directly from amazon because I think it's safer and cheaper (I aim for the free shipping).
I've ordered from Amazon since 2006, and I usually order books for my classes. They ship pretty quickly. My shipments usually arrive about 3-4 days (at most a week) after I order. I always try to get their free shipping by ordering over $25, but right now I have the prime account (free for students) w/amazingly fast shipping.
My one complaint is that if you send a present & don't opt to have it wrapped, they put the note in the box with the present. I thought the note would be a sticker on the box, but it's not. By the way, their shipping is through Fedex.
Overall, I'm pretty satisfied.