It is worth it, there are some interesting views although not very pretty (such as when the line seems to run right through a huge chemical works). The ride is actually very smooth, and even though I am often scared of heights I didn't have any problem. Hang around a couple of minutes after the train arrives at a terminus to see the ridiculously tight curves on the end loops.
Wuppertal is not in the same transport union as Koeln. Koeln is in the VRS (Rhein-Sieg) while Wuppertal is in the VRR (Rhein-Ruhr). There is a Nordrhein-Westfalen Ticket that works just like the Bayern-Ticket and will cover both rail and the Schwebebahn.
Another point of interest is the Burgische Museumsbahn (http://www.bmb-wuppertal.de/) at Kohlfurth, which is a preserved section of the old cross-country tramline between Wuppertal and Solingen and can be reached on the regular bus route that now links the two towns. They only operate every other Sunday, but you can visit the depot at Kohlfurth on all Saturdays or Sundays.
You might also be interested in the trolleybuses of Solingen, the largest by far of the three remaining systems in Germany, which connects with the western terminus of the Schwebebahn at Vohwinkel.