Generic walking feet are like generic processed meat products. Sometimes they will get the job done and sometimes they are the screaming mimis. Not all machines have a OEM walking foot available. If you buy generic you pays your money and takes your chances.
Personally I think for the occasional home user DIY person they are overrated compared to the expense. For commercial use they are almost essential but the occasional user is investing a lot of money if they don't use it a lot. They can be cranky to adjust especially if you change your stitch length or make drastic changes in fabric. They make most sense for higher volume in termso of cost effectiveness.
Remember, once the first line of stitching is in the fabric is stable and a walking foot is needed a whole lot less. Nothing wrong with them if you like your otys and can get one made for the machine you have. But below a certain level of production _I_ think they lose their cost effectiveness.