Is housecurve easier to use than REW?
I have yet to try REW... But from what I have seen, I would go out on a limb and say yes.
The two apps are very different animals.
REW is PC-only (Windows, MacOS or Linux) and requires an external microphone, for proper measurements.
It is free, provided you have a PC and microphone - but from the guides I have seen, it takes some time to work with, for a beginnner.
HouseCurve is iOS-only (iPhone or iPad) and uses built-in microphone - but can also use external microphone.
It is a rather simple one-device / few-clicks app and can airplay sweep-sequence directly to WiiM - but it costs (10$?) if you want it to output equalization parameters for you.
Both apps can perform measurements and output PEQ-parameters for use with WiiM.
But currently you cannot import PEQ-files in WiiM. So for both apps you will need to enter the app's suggestions manually in WiiM's PEQ.
EDIT: Sorry, just saw your earlier post about REW. So I guess that you are already familiar with that.
/Martin