We have them at our sports institute and I spent many a Tuesday lunch hour on them last season. They're cruel mistresses. Very cruel mistresses.

When you set the load for a certain wattage, the computrainer will compensate for variations in cadence (speed) to ensure you're working the correct load. There's no escaping those 300w intervals on that thing.

The 3d course thing is kind of neat too, a few guys used it to train for the sugarloaf road race last year.

But, if you already own a trainer, you may be better off just buying a power meter.