After 6 weeks of constant use with two iPhone 4 units, Mossberg found that in areas with "average or strong AT&T coverage" the iPhone 4 generally performed better than the iPhone 3GS, but performed worse than the 3GS in areas with weak coverage. One iPhone 4 was a review unit provided by Apple, while the other was purchased by Mossberg.
Mossberg took issue with Apple's claim that the iPhone 4 performs better than the iPhone 3GS in areas with poor reception. In his experience, compared to the iPhone 4, the iPhone 3GS actually dropped less calls and showed a 'no service' status less often.
Mossberg's conclusions were consistent with his original appraisal of the smartphone. In his initial review, Mossberg praised the iPhone 4's design and features, but criticized the lack of network choices.
Since AT&T "operates a network that has trouble connecting and maintaining calls in many cities" and has abandoned unlimited, flat-rate data plans, Mossberg was unable to recommend the smartphone to people in poor AT&T reception areas.
Regarding the 'death-grip' issue, Mossberg noted that gripping the phone would cause the signal bars to "fluctuate," but didn't find the issue to be of serious concern. In some cases, he noted, the bars actually rose when the left-hand seam between antennas was deliberately touched.
Mossberg concluded the post by acknowledging that the iPhone 4 worked better for him than the iPhone 3GS in decent coverage areas and reiterating that he does not recommend the handset to users who suffer from poor AT&T reception where they "live, work, or travel."