It is well worth visiting the cable car station, even if you do not want to take the cable car to the top of Mount Teide. There is a great viewing platform over the surrounding area, they also have quite a nice cafe and a little gift shop. There is lots of free parking on the hill on the way up to the station.
If you decide to take the cable car to the top of Mount Teide, this is a great experience too. The journey takes just under 10 minutes and you climb up to 1,200 metres. Apparently there can be extremely long queues here, sometimes people queue for as long as 3 hours to get on the cable car. We did not experience this at all though. We got there just before the last cable car ride of the day, and found no queue at all.
You can't actually go right to the summit of Mount Teide in the cable car. To do that, requires a special permit. You get out just 500 metres below the summit though, so that still is quite something!
The cost of the cable car is quite expensive. It is really cold at the top as well - apparently it is always freezing up there. You do need to be prepared for this and bring very warm clothing - a light jacket would not be enough. It can be deceptive down below on a hot sunny day, you can hardly imagine this would be possible. They do say though that in winter on Tenerife, you can sunbathe at the bottom of the cable car run and have a snowball fight on the top of Mount Teide 10 minutes later.
The cable car holds 35 passengers. The ride up is quite good fun. Unfortunately it is absolutely impossible to tell in advance whether or not you will get a good view from the top. The clouds seem to gather extremely quickly and the weather literally changes all the time. We experienced this even at the lower level, sometimes you got a great view of Mount Teide, 2 minutes later, completely unexpectedly, it was totally covered by cloud. This is the same at the top.
Another thing to remember is that at the top of Mount Teide, the air is very thin, people with certain health conditions should not go up. Everyone needs to be aware of this - you do find yourself panting a bit even with very little exertion.
It is a great experience taking the cable car to the top of Mount Teide. The Guanche people thought Mount Teide was where the devil lived - it is exhilarating to go to the top of it! If however, you do not want to queue, or pay the expensive ticket prices, I thought you still got a wonderful view from the cable car station without going to the top. You can still see all the way over the caldera and the wonderful lunar landscape from here.