The majority of armchair pundits maybe, but ask the people who have actually achieved something in RL ie the SL winning coaches, his fellow players and people who actually work within the game and they will tell you different, I wonder who's right?.
If you expect a SL winning coach to share his genuine opinions with a stranger then you're naive beyond imagination. Whether they think he's been useless, average, awfull or whatever they're never going to say that in conversation, interviews or in any articles they write. I guess you'll just see that as another easy, win win position for the anti Sinfield mob to take but hey ho whatever!
For the record, I like Sinfield, I respect Sinfield, I think he's been an absolute Legend for Leeds Rhinos and will rightfully sit up there with Lewis Jones, Arthur Clues, John Holmes as one of Ledds all time greats. His domestic form has been consistent for a decade and his leadership of his club throughout their most successful period ever has been amazing. He's a role model that any aspiring young player can look up to and as a coach and parent I'd encourage kids to learn from his example.
Unfortunately he's never been able to take his club form into a Test Match and sure that frustrates him more than any of us. I wish it weren't true because we could do with a payer who does internationally what Sinfield does for Leeds but after 30+ attempts its long past the time to admit that it's not ever going to happen and move on.