Yeah, It's great for all type of apk manipulations like the merging of split apks, extracting apks, decompile apk with easier, frida-gadget injection and many more options... That makes it good choice for security researchers...
But it's in development mode, there i got some bugs on it mainly during the frida-gadget injection, for complex apps which obfuscate there MainActivity class, there it sometimes patch into different path (late running smali) , have some minor issues in apktool version compatibility (something like usage of newer command args on older versions).
But rest of it the structure is well maintained and runnable with some manual tweaks...
So was just looking for contributors to make this tool error free even better for everyone.