Good if you need a sim urgently to perform a sim swap or want to share your good experience with another. Good if you can pick up a spare sim for travelling to Europe, if Giffgaff extends the goodybag to include Europe.Good for the company, it makes business sense.
Not so good for recruiters - especially if shop bought Sims have the same perks as recruited ones.
Not so good - my chances of becoming a super recruiter have nosedived.