Sony's latest Android phones are probably the most exciting thing the Japanese company has done in the smartphone arena to date. I mean, Sony unveiled a flagship phone that is water and dustproof.* (to one meter for up to 30 minutes.)
That alone is something worthy of attention. The sister device, the ZL, is a slightly downmarket version of the phone, though even saying that much isn't exactly fair. There's nothing particularly worse about the ZL, other than the fact that it lacks the glass backing of the Z, or its tolerance for wet and sandy situations.
In fact, many people may prefer the ZL - its headphone and microUSB ports are exposed, whereas every access point on the Z is guarded by a watertight cover that has to be pried open to access the respective port.