As a car driver I remember my last visit to Cambridge with a sense of fear; fear that I would accidentally collide with one of the many cyclists. And yet, when I was a student there, cycling didn't worry me at all, and I did it for all of my 3 years.
I've now lived in Milton Keynes for nearly 40 years, and I now feel that the cycle/pedestrian Redways local to my area (Great Linford, Neath Hill, Stantonbury) are much less used by cyclists than they were ~15-20 years ago.
That's quite interesting, as over in Bletchley I see just as much cycling as before, if not more, and the racks in front of MKC station are a curious bit of Dutchness in the UK. One thing of note is that many of the cyclists are Eastern Europeans to/from work in the warehouses etc - what that does mean is that you get curious standoffs between British people who ride on the left and others who forget that you should! (The Redways are intended to be treated as a traffic-free country lane - cycle on the left, walk on the right, don't block the whole width by either mode).
One of the big advantage of the Redways is the possibility of "free range kids", for what it's worth. It was Merseyrail that gave me that mobility as a kid, but cycling wasn't great (though helpfully the A59 from Aughton most of the way to Aintree has Dutch/Redway style cycle lanes on both sides and long has had). In MK public transport is decidely iffy but kids can walk and cycle without crossing roads to almost anywhere. There's also that living in a 1970s bit of Bletchley my house fronts onto a footpath/cycle path (not a Redway but used for both in practice) and kids play out like they did in the 1950s - must have been a great place to grow up.
That was when I got punctures from glass bottles smashed below the underpass bridges, and found that away from the housing estates, the cycle tracks were very bumpy as a result of tree roots raising the asphalt. Time for the Tour de France to visit MK and get the Redways properly sorted!
A lot of work has been done on them in recent years and much of the subsidence and tree root issues have been dealt with. The glass is dealt with, as noted above, by the use of Schwalbe Marathon Plus or Continental Ultra Gatorskin tyres - fit either of them and you simply will not get punctures ever.