The most important aspect of this release is that Views should now be PHP 5.3 compatible, and the grouping features should finally really be fixed.
As of now, Views 2 will be accepting fewer and fewer patches that qualify as new features, as work on Views 3 is proceeding at a good pace. New features should, unless they are really important for some reason or other, be moved to Views 3 which should be expected to go beta sometime in the spring.
#622602: Missing ORDER BY in some views with tables due to incorrect test for default table sorting.
#623498 by marcp: total_rows should be filled in if fetching all records.
#535206: Attachment displays repeat exposed filters because exposed filters were left hanging around during cloning.
#450346 by lefnire: Inherit Exposed Filters sometimes hides part of the parent exposed filters
#550560 by donquixote: Fix unterminated string in views.help.ini that breaks under php 5.3
#592476 by Garrett Albright: Remove redundant CSS from views-list.css
Tagging an alpha release of 3.0 -- this release exists mostly because 3.0 is about to get a lot less stable, and I know people are using it for the query backend stuff. This gives a relatively stable point to work from without getting nastily hung up on some of the new features that are going in.
Note: Views 2.7 contains some rearrangment of the order of field rendering. While I didn't see any errors or hear of any errors due to this, it may affect some external style plugins. If you have a problem with how fields render and are using a non Views-core style, please doublecheck with the 'table' or 'unformatted' styles and see if the problem persists. If it does not, it may well be the style provided by a module.
Table style when not overriding sorts put sorts in wrong order.
#488908 by sl27257: "Node: Has new content" only worked when exposed.
#451110 by wonder95: Fixed missing word in transform case help text.
#385904 by JirkaRybka: Prevent duplication of id edit-submit on views exposed form.
This release is primarily a large number of bug fixes. Please note that one fix required an API CHANGE. This change affects all modules that use the Views API and those modules will likely cease to function.
There are a couple of bugs in Drupal 6.2 that are fixed in Drupal 6.x-dev that make it very important that Drupal 6.3 is used (or, since that is not currently available, Drupal 6.x-dev).
This beta release includes a few forgotten features or features I didn't have time for, or features submitted by users that were too good to pass up. Plus, a lot more of the help files are written, if badly.
Specifically: comment RSS, major updates to exposed filters, a bunch of new default views, important fixes for node language filter, taxonomy term with depth argument, argument defaults to try and get 'node' and 'user' ids automatically from the URL, and a whole bunch more I have forgotten.