Frenchy brings up the wattage list. Back in July, a lot of the mentally-advantaged guys there (Coggan, Robert Chung, etc.) put two iBike+Powertap files through the wringer. Their comments are more meaningful to me than any company-backed study anyway, since they're unbiased. One file was just a normal ride, the other set out to exploit the iBike's weaknesses. The first looked, as Chung said, "surprisingly good." The second not so good, particularly in some sections.
Since there seems to be a lot of discussion of the iBike on here, I'll include some links and data that I bookmarked from the wattage list. Here are a few stats that James Smith compiled from the good ride, available (with charts) at http://www.pearlandcyclingclub.org/pt_ibike.xls:
Powertap, iBike
Average - 254, 254
Normalized - 276, 279
NP30 - 292, 295
NP20 - 299, 301
NP10 - 303, 309
NP5 - 316, 322
P30 (30 second avg) - 445, 524
(cite: http://tinyurl.com/rpzfq)
y=.9774x, R^2=.562 (1 second)
y=.9896x, R^2=.7107 (5 second)
y=1.0006x, R^2=.8863 (15 second)
y=1.0027x, R^2=.942 (30 second)
(cite: http://tinyurl.com/lqkyb)
And from the bad ride, available at www.pearlandcyclingclub.org/pt_mod2.xls:
P_avg_PT=241 W, P_Norm_PT=290 W
P_avg_IB= 291 W, P_Norm_IB=394 W
(cite: http://tinyurl.com/pjwdm)
The bad ride wasn't consistenly off -- most of the time the data was good, but there were a few sections (the rider said on rough roads) where it would go bonkers, and they threw off the averages for the whole ride.