Their cartridge style filters are pretty good. I've been buying ST filter for my Ecotec 2.2 from WM for years without any issues. Their suppliers change often and what I've noticed filters from China are pretty poor quality. South Korean and U.S. made filters are top notch. I've also seen those cartridge filters made somewhere in Easter Europe (Romania, I think) which were also OK.
I haven't opened any regular ST filters in the last 5 years, but I think they should be OK. My dad has been using ST filter in his '95 Accord and never had a problem. For the newer car I would definitely go with something more proven like M1, K&N, Bosch, or Purolator. Though I have not seen any difference in cartridge style filters among the brands. If anything I purchased 2 purolator filters for Ecotec a few years back and they were very poorly made compared to ST.
Again I can't really comment on regular 'closed' filters.