As much help as you want.
As little as you need.
The interlinear line is a help — not an obligation. You switch it on when you need it, and off when you don't. If you read without the interlinear line, you're still not alone in the text: one click on a word opens the iSpicker — with the translation and, where they exist, the different meanings. This creates a natural path: at first you read with the translation line above every line. Later you only need it for difficult texts. Eventually you only click when a word really holds you up. That's not a level you have to unlock — it just happens, while you read.