Looks like n+1 (knobbly-tyred mtb) and canal towpath to me.
http://www.gps-routes.co.uk/routes/home.nsf/RoutesLinksCycle/birmingham-to-wolverhampton-cycle-route# refers.
Of course, this is me knowing buggerall about the route in question, just hunting around for a map.
This is the one I referred to above. Veterans of the Tunnel Ride will be familiar with about half of it. It's ridable without getting covered in mud for about 2 weeks a year, and surprisingly hard work. As Basil says, it's also dull, to the point where if you do it more than a couple of times you're likely to want to ride into the canal just to liven things up a bit. And there's something particularly soul-destroying about watching people hurtling past on a nice warm dry train when you ride it in winter.
There are a handful of dodgy bits around bridges where slippery bricks, broken glass or persons of low moral fibre may constitute additional hazards.
That said, I reckon it's a prime candidate for the Sustrans-if-they-had-a-budget treatment. For the most part the bank is wide, with good sightlines, and it's a flat and direct route between places that people actually want to travel to. If someone were to put down a couple of metres of decent quality tarmac
[1], with some lighting around the pinch points to improve social safety, it could easily become the Midlands' answer to the Bristol-Bath railway path.
[1] The current batch BCR of gravel-topped towpath improvements stop about halfway to Smethwick. After that it's deteriorating hardpack and outright singletrack.
