Below are a few links I have found that provide information on SAP BW Powered by HANA. I will include a brief summary and the type of information you can expect from each link:

BW Powered by HANA Equals a Supercharged BW System: Link 

The above article will “summarize the major areas of performance improvements with SAP NetWeaver BW on HANA and  give some examples from Ramp-Up customers (RU)  or Proof of Concept customers (POC)”

SAP BW Powered by SAP HANA Frequently Asked Questions:

The link provides mostly marketing information and high level migration questions. FAQ Link

HANA In Memory Optimized Infocube Video Presentation:

The link provides information on BW powered by HANA including In-Memory optimized InfoCubes and Query performance. It can be technical at times but should provide useful migration information if you are familiar with SAP BW terminology. In-Memory Link

General SAP BW powered by HANA – Informational Power Point Presentation (Slide Deck):

The link provides a general overview and benefits. It is mostly marketing information. Link

Reporting on HANA but using SLT or Data Services to Load HANA:

This article is technical and a little hard to follow at time. However, I read it over a few times and found it to be informative. Link