Bugs fixed
Getting trapped in graveyards when collecting BONUS
Boss 3 disappearing
+ all other reported bugs should be fixed.
Difficulty levels
There are now 3 difficulty levels. Each difficulty level keeps its own separate progress, and 'gold' stats are capped differently for each level.
EASY (stats cap

NORMAL (which is comparable to the pre-update difficulty - stats cap 6)
HARD (stats cap 4)
Standard / Challenge games
The standard game no longer finishes after the last boss, but will loop around again at a harder difficulty.
There is now also a Challenge mode, which finishes after 4 levels (ie how the game was previously working). In Challenge mode, there is no carry-over - you have no starting boosts, and bonus items/weapons don't need unlocking.
Challenge mode has leaderboards for high score in each difficulty, and the quickest run time for winners.
Gameplay rebalancingThe game should no longer be quite so easy to finish in co-op mode.
Items are now be dropped at slightly more reasonable points.
Once you have maxed out your stats, you will no longer be given useless stat upgrades, but other things instead.
At maximum experience level, you will now continue to get loot drops for extra score.
Extra window scaling options
3x and 4x window scaling for people with high-def screens.
Shop
Extra items available in the shop now (you can sometimes buy coloured gems or bonus letters).
Prices now vary according to how many of an item you have, and you can buy some items multiple times (e.g. extra health).
Bonus game
There are now far more coins to collect in the bonus round, and they are more fairly distributed.
Updated lighting visuals.
Jumping tweaked to be a little more forgiving.
Bonus game can now be paused.
Leaderboards
Leaderboards now show more entries, and there are separate boards for each difficulty level + new boards for challenge mode.
Bosses
All bosses have been tweaked slightly (and vary with difficulty).
Controller Support
The only menu not supporting the controller (the controller config menu) will now accept controller input.
Achievements
All achievements should now unlock properly. The achievement for collecting every item in the ledger has been change to now only require 100 different items to be found.
+ lots of other little bits & pieces have been tweaked / improved.