I'd say the trainer is a great workout tool, except that it's about as exciting as watching paint dry. You put out a constant workout for however long you are on the thing, and with the resistance settings you get a good workout.

I'd also pay no attention to the speed you are going or the distance, I have a cheapy Nashbar trainer, I spent some time to retro-fit my cyclometer to the rear wheel only to find out I was riding so damn slow on the thing, I could average maybe 12-13mph (roughly 20km/hr) for any period of time, I was more than a little discouraged by that info (until the season came around and I could start riding on the road again).

Then I found this page -
http://www.geocities.com/almost_fast/trainerpower/

If you know those numbers the trainer is an even better tool.

Andrew