jet.com is OK. For most of the stuff, they are reliable but books, they rely on Barnes and Noble and at times there is delay in delivery.

Also your discount increases the more items you add to the cart, so jet actually encourages you to make one big shopping cart with their system.

I've been comparing and buying on either Jet or Amazon recentlly. As a result, I've been buying on Jet more frequently. Jet has a smaller selection but they usually have a good enough range on the price-value curve that it's not a big problem. Like for like, they are indeed cheaper than Amazon and free 2 day delivery is always a plus. Of course their model is lower prices with a bit more delayed deliveries.

I just ordered a few things from Jet.com and it was split into 3 shipments. A shipment of 1 item came within 2 days. A shipment of 3 items is on its way somewhere (although the tracking number gives no real details). The final shipment of 1 item is still 'processing' 4 business days later. It was supposed to be 2-5 day shipping, but I don't see the third item getting to me by tomorrow. We'll see, I guess.