I started using MyWhoosh in late December. I setup the triathlon training plan they gave. I works pretty well in ERG mode. I haven't run into any problems really, though other say it is buggy.
The only thing I am suspicious about is the training plans. I don't know if the workouts are working me hard enough. I am in late base training plan for 4 weeks.

It seems like few people know about this app and that it free.