In my opinion M&S is great for staples - shirts, jumpers, work trousers, etc. - but when they try and do anything 'quirky' or 'trendy' they tend to get it a bit wrong, and Per Una sort of epitomises this. I don't think it's really an age thing tbh.
This jacket is not my style but it's not horrible. I do like the colour scheme for spring/summer - you could probably get quite a lot of wear out of it.