I too have been tinkering, and I wonder how different the PCB formats are. Perhaps a little hex editing might make files compatible?
Anyway - my observations so far:
Fast to load than AD, but so it should be. Still shows as DXP.EXE in the task manager though
Loads existing Altium projects, can open / edit libs, schdocs. NOT PCBDOC.
Wont load CAM files from AD
Hotkeys are a mess. Some you are used to from AD work, some don't.
i.e. "select all connected" (CTRL-H) works.
ZA / ZB (Zoom All, Zoom Board) don't work. It's right click and hunt time.
PT (Place inTeractive Routing (aka Place Track) DOESN'T WORK. You have to hit the Route icon on the ribbon. EVERY. SINGLE. TIME.
That's a deal breaker for me, right there.
Generated new pcb quick - imported using libs as defined in existing sch files
Option to change colours to AD colours. Red and Blue top / bottom layers FTW! THe light blue / lighter blue defaults of Circuit Studio is stupid.
CANT DEFINE BOARD SHAPE FROM SELECTED OBJECTS. NOOOOO
CANT IMPORT DWG/DXF - arrrgh (i.e. case drawing)
CAN define polygon pour from selected items. Oh come on!
Netlist tools are there - win - i.e you can colour individual nets, hide / show selected ones.
Hierarchical sheets work, but no rooms, so multichannel duplication isn't there. Old school copy paste it is hen.
To be frank, these are limitations that I'd accept for Circuit Maker, not a paid tool.
Come on Altium, let us edit the hotkeys at least!!