1. A computer-implemented method of text passage difficulty estimation, comprising: generating, using a computer processing system, an informational text scoring model, wherein generating the informational text scoring model includes: identifying a plurality of texts from a corpus of texts that are informational texts; determining one or more metrics for the informational texts; and configuring the informational text scoring model using the one or more informational text metrics; and generating, using a computer processing system, a literary text scoring model, wherein generating the literary text scoring model includes: identifying a plurality of texts from the corpus of texts that are literary texts; determining one or more metrics for the literary texts, wherein the literary text metrics include one or more metrics that are either not included in the informational text metrics, or are included but are weighted differently; and configuring the literary text scoring model using the one or more literary text metrics.