Over the course of the past couple weeks, I have spent 4 nights/days in Quito. This was my first trip to Quito. I found the taxi drivers to generally be courteous, professional, and (most of them) friendly. I'd say I took about 15 taxi rides in registered taxis. Only once did the driver use the meter. Otherwise you just hop in, explain your destination, and negotiate a fare. The fares were typically $2 or $3 (extremely cheap for distance traveled).
The one time when the driver used the meter my fare was 81 cents. This was for a route that I had previously taken in another taxi that I "negotiated" to $2. So my negotiated fare was more than double the metered fare. Who cares? It was 81 cents vs $2!
A note about explaining your destination to the taxi driver...
My experience is that the taxi drivers don't really know specific destinations (like hotel names or restaurants). For example, I stayed at the Mercure hotel in La Mariscal. It's in a prominent location. Not one taxi driver knew where it was when I provided just the name of the hotel.
However, when I provided the cross streets, they all knew. So I'd hop in and say "Mercure hotel, Amazonas y Roca"
Likewise, we went to a restaurant called La Boca del Lobo. The driver had no idea. Then I said, "La Boca del Lobo, Reina y Calama" the light bulb went on.
So unless you're traveling to a very well known destination, know your cross streets.