I was outraged when they started charging and replaced the complimentary offer with mixed nuts, vegetable crisps and raisins, without lowering the steep prices for first, so I never thought I'd encourage the service, but I tried it a few months back and found the breakfast is absolutely fabulous, so yes.
For comparison purposes, the Avanti "Great British Breakfast" is usually good quality but very small, and although the "Full LNER" is bigger, I find it to be more slapdash quality - you know, stringy bacon and hard yolk, and they don't serve black pudding or tomato. (That said, it's better than a bacon roll which is the most you get on northbound services nowadays, disgracefully) The TfW Breakfast is enormous, and very good quality.