Is it worth upgrading from the original 24-70mm GM?

Yes for most shooters. The GM II is lighter, focuses faster and is sharper wide open, which matters for events and handheld work. The original remains capable if weight and autofocus speed are not priorities.

How does it compare with the Sigma 24-70mm f/2.8 DG DN Art?

The Sony is lighter, has an aperture ring and faster autofocus. The Sigma is close optically and cheaper. Choose the Sony for autofocus and handling, the Sigma for value.

Does it work on APS-C Sony bodies?

Yes. On APS-C it gives a 36-105mm equivalent field of view. It is designed for full-frame E-mount and works on both mounts.

Is the lens stabilized?

No. It has no optical stabilization and relies on the camera body's in-body stabilization. Most recent full-frame Sony bodies include IBIS.

What is in the bundle?

The bundle pairs the FE 24-70mm f/2.8 GM II lens with a flash unit. Check the flash model and included accessories before ordering.

How close can it focus?

Minimum focus distance is about 21 cm at the wide end and 30 cm at the telephoto end, closer than the previous version, which helps with detail shots.