Does this watch really never need a battery?

Yes. Eco-Drive charges from any light source through the dial and stores power in a rechargeable cell. Citizen rates standby at about 8 months in the dark.

Can I swim or shower with it?

Yes. It is rated 100m (10 bar), which covers swimming, showering and snorkeling. It is not rated for scuba diving.

Is the crystal sapphire?

No. It uses mineral crystal, which is shatter resistant but scratches more easily than sapphire.

How big is it on the wrist?

The case is 45mm wide and 10mm thick, and the watch weighs about 147g. That is on the large side, so it suits wrists roughly 7 inches and up.

What comes in the box?

The watch on its stainless steel bracelet, a Citizen box and a manual. The band is sized for about an 8-inch wrist and links can be removed.

Is it worth buying over a sapphire crystal Citizen?

It gives you Eco-Drive, 100m water resistance and a two-tone bracelet in one watch. A sapphire model resists scratches better, but you give up the two-tone look and usually pay more for the same features.