I have very strong opinions on this topic, so here they are, summarized.
(Whysnow is 100% dead on in the 4th post above).

The Premium: Ball diverter to top playfield (top of orbit) is prone to failure and causes combo ruin.
The upper playfield just is not that fun, and slows down the game.
The extra ball shot is better placed in the Targaryn dragon lane rather than Martell - more risk/reward.

Most glaring flaw:
In this game, during normal play the ball often travels part of the way up the middle (left) ramp and comes back down.
On the Premium - balls that do this are under the top playfield, obstructing the view and making saving the ball brutal and unfair.

Go Pro - don't look back.
Thrones is a great, underrated Stern title with incredible scoring combos and terrific risk/reward factors.
The game does badly need one more code upgrade, to correct some flaws and balance the houses at start of game.
Here's hoping Stern delivers, to celebrate the final season coming in 4 months.

That's something I did not know. Thanks - now I'm dying to go try it.

I did trigger the endless ball save couple weeks ago during those 2 modes combined?
Are you sure it's a bug?

That is the only time I ever made it to Midnight Madness Multiball too - and have no idea what I did to do it.

That's so funky!
Thanks for the note-

Freaky mode - you think the machine is malfunctioning, at first.