From the changes.txt

Unangband 0.5.1 "'Oops. I did it again' again" release
- Reordered monsters in monster file, rendering save file
incompatible for the first time ever since Unangband released.
However, it allows use of graphics in the game, using Angband
2.9.6 pref files.
- Fixed bug with loading dungeon in campaign mode.
- Fixed bug causing visual weirdness due to tab replacement
in strings.
- Fixed bug preventing players learning spells that was
introduced in upgrade to 2.9.6.
- Fixed some minor monster changes.

Unangband 0.5.0 "This is Dedicated" release
- Updated help files to include new options.
- Restructured help files to format similar to Eyangband.
- Removed a number of monster AI options that are no longer
used.
- Made it so players descending to ground floor of tower, gets
placed inside the tower.
- Use revised knowledge code from Eyangband.
- Change auto-inscription code to use the revised knowledge
code (~) instead of the old auto-inscription menus ($). In
particular, you can (c)opy and (p)aste auto-inscriptions,
letting you very quickly configure large number of auto-
inscriptions in a manner similar to many auto-squeltch
implementations. (No "squeltching by quality" supported though).
- You can now inscribe @x* on an item, where 'x' is any action,
and that item will always be picked when you attempt to perform
that action. This is very useful in 2 circumstances: when you
want to duplicate the {SQUELTCH} inscription from many other
variants, by setting up auto-inscriptions with @k*, and when
you only have 1 stack of arrows/bolts, shots inscribed with @f*,
saves you a keypress to fire.

Unangband 0.5.0-pre1 Bugfix release
- Added more dungeons and reorganised somewhat.
- Added some more uniques to populate new dungeons.
- Removed Red Deaths (Were from Kangband anyway).
- Staves were losing to hit and damage bonuses.
- Fixed major bug with campaign mode.
- Scrolls of teleport level had incorrect s_info.txt entry
(Should have been 10).
- Made frogs slightly deeper and all toads spit at a distance.
- Loose rocks not working properly because of paranoia.
- Make metallic centipedes metallic.
- Enchant armor and enchant armor to-resist had incorrect
s_info entrys (should be 16 and 49).
- Mushroom of mana has incorrect s_info.txt entry (Should
be 20).
- Improved curing from Cure Light/Serious/Cure Critical/Cure
Mortal Wounds.
- All goblins should be HURT_LITE.
- Wooden chests only drop gold (At this depth, it is more
valuable than garbage).
- Broken cages should be MOVE and not TUNNEL.
- Upgraded much of code base to Angband 2.9.6 (This excludes
Lua however).
- Changed self knowledge code slightly.
- Removed ALLOW_OBJECT_INFO define as it is always on now.
- Added improved ability to inspect objects from Eyangband.
- Fixed long standing bug causing consistent crashing when
attempting to load a save file with a dead character.