It’s more durable. Overheating regular PET makes it hazy and brittle. Not with PETG filament: The added glycol prevents the material from crystallizing and becoming breakable. The new material is also highly impact-resistant.
Unlike PET, is it RF sealable.
Professional printed, it also can be sterilized.
These are the benefits of PETG filament for 3D printing:
PETG filament has the reputation of combining the benefits of ABS (stronger, temperature resistant, more durable) and PLA (easy to print) in one material.
The layer adhesion is usually excellent.
You can expect less trouble with warping or shrinking of your prints.
Also, you can have the material, prints and misprints recycled. This doesn’t mean you should start printing irresponsibly – sustainably speaking, it’s still plastic, which has to be recycled properly.