Here's an excerpt from the project home page:
We are aiming to solve several key weaknesses of the stock front-end:
- Greenstone's cryptic URLs of unusual size are a fail for user comprehensibility, search engine crawlers, bookmarking, etc. . .
- Though extensive customization of the display is possible, there are some stopping points where modification of the C++ source is required.
- The customization that is supported is via a system of micro-templates referred to as macros. This system is so heavily nested and cross-referenced that it is very difficult to conceptualize how any given page is generated.