Previewing is a big part of creating content, and people are currently very confused by preview being shown in the back-end instead of front-end.
The meta tools we present users; menu, revisioning, authoring information are cumbersome and often result to conflicting mental models.
Text formats are still somewhat of a mystery to most of our users, they miss a WYSIWYG editor.
The lack of a common workflows like save as draft is a disappointment.
Tools for moderating content are almost non existent, our filters are hard to use and search is non existent.

The Relevent Content Bean essentially provides your site administrators with a light-weight query builder (build on top of EntityFieldQuery) for creating blocks that contain dynamically-filtered listings of nodes. Like Views, Relevant Content Bean allows you to select the number of node results to display, apply filters to the list of returned nodes, change the display options for these nodes, and manage the sort order of your results.

use one exposed string filter to search on multiple fields.

Bear in mind, that, for now, only populates STRING exposed filters, so those filters that take an array (options) or special types won't work, although it may not be difficult to extend it.

...you have "First Name", "Second Name" and "Last name" set up as node or user's fields and you'd like to use one expose filter to search on any of those fields.

bforchhammer's sandbox: adds a formatter to a fieldgroup that puts labels of fields on the left side and contents on the right.

Front-end performance is also a critical priority for Zen. That’s why Zen 5’s markup and CSS footprint is so small. After turning on Sass production-mode compilation, the total CSS is only 14k; this includes the layout, vertical rhythm support, print styles, all the appropriate vender prefixes (like -o and -khtml), CSS3-prettified tab styling and the 3 menu images that are included via Data URIs into the CSS. Zen includes no images and only 2 JavaScripts (which are only loaded conditionally by IE8 and lower, but also minified and pre-aggregated together).