Ask HN: Are we about to get screwed with this iOS publishing deal?

Our startup is developing our first game on iOS (free with in app transactions) and want a mobile publisher to handle marketing etc.

One publisher has proposed the following:

IP owned by studio 18 month right for all language, all location publishing right on iOS and Andriod platform publisher responsible for the translation to other languages, marketing, advertising and user acquisition revenue share on the in-app purchase and paid revenue ( after all channel cost deducted) Tiered level of share ratio based on monthly revenue amount. An example here, $ in USD monthly revenue : From $0 to $x , 50% publisher / 50% Developer Next $x to $y, 55% publisher / 45% Developer Then $y+, 60% publisher / 40% Developer

Anyone with experience working with iPhone publishers care to comment?

ps - I know this is "how long is a piece of string" question, but any guidance is welcome..