Changelog:

New Features:

Search functionality with on screen keyboard
Allow sorting of app list by: most recently updated, download count, alphabetically, download size, and randomly
Add new "Advanced" category including some system/hekate modules
Redesigned "App Details" screen to show much more information about each app such as long scrollable description, download count, download size, and last updated date
Added feedback reporting for any app to collect data about what works and doesn't work. This feedback will be passed along to the app's author if appropriate
Enhancements:

All touch and controller controls refactored and more responsive to input (highlights, buttons, etc)
Add four-column "wide" view activated by pressing L or ZL in the app listing
New offline screen when internet connection isn't detected instead of empty progress bar
List other apps by the same author from the details page
Bug fixes:

Switched to curl instead of old hacky HTTP downloading curl
Empty folders are now removed upon uninstallation of a package
Corrupt cached icons should no longer freeze loading
Uses romfs for storing images instead of an external folder
Some settings for cleaning up any empty folders leftover by the old app and wiping the icon cache

Installation:

Switch: copy appstore.nro to sd:/switch/appstore/appstore.nro, and run via hbmenu
Wii U: copy appstore.rpx to sd:/wiiu/apps/appstore/appstore.rpx, and run via HBL
OR: extract the right *-extracttosd.zip for your platform to the root of the SD card
Changelog:

Switch:

new theme category + allow theme installation
NRO launching after installation
uses GPU to render (smoother)
Both:

faster downloads
can actually exit with minus button
misc category added
Wii U:

synced with switch codebase! Now using SDL2
can search now!
can control without touch screen
can scroll and read more details about packages (size, changelog, etc)
can install files anywhere on SD (Retroarch, haxchi, etc updated)
sort apps, smoother scrolling, and other quality of life things from syncing with Switch
The PC build has also started migrating to Buck + Buckaroo for building and dependency management. It is my long term goal to use the same Buck configuration to compile across all platforms!