Tron has one, but Tron: Legacy doesn't.
In fact, a lot of the recent Disney steelbooks don't. John Carter, Mr. Banks and The Muppets don't have pictures on the spine. It's annoying though that there's no consistency with this release compared to the other Disney classics (excluding title-less steelbooks. By and large they've all matched. That said...
Aladdin doesn't have the Disney title on the spine.
Cars 2 has BBFC/IRL certificates (admittedly an early release, and HMV not Zavvi).
Monsters University has the Blu-ray logo sideways.
Treasure Planet has a Blu-ray logo at the top rather than the standard Disney Blu-ray logo, the spine title is far too low compared to the others (although they're a bit all over the place anyway) and there's no picture on the spine. Don't be surprised to see any further classics follow suit with this design.