I wouldn't be without mine. My Horizen has it built in, I bought the 1/4" foot and the SID foot that works on the walking foot. I did not want to use the ones that came with the machine because that would not work with the walking foot.
The walking foot helps to keep your fabric even. When it is just the feed dogs on the machine, it tends to pull the bottom fabric a slight bit more. On my old machine I did everything I could with the walking foot on the machine, it too was a Janome.