I've had my HAC 4 since x-mas and have loved it after getting used to its functions (yeah the softwear and a few other things seem clumsy at first). My riding partner eagerly asks what the grade of a hill is, temperature, cadence...like others have said, it's got the most for the buck and I've found it to be fairly accurate in those areas. I agree if you want watts get the powertap.

One thing I REALLY like about the HAC; my strap battery went dead so I took it in for a replacement at a local store. Less than 4 dollars for a lithium battery later it's up and running. Another riding partner had her Polar strap battery die. 40 dollars later she'll be up and running as they don't open to change the battery, they're disposable essentially. I like that the HAC doesn't have the hidden charge.