Google's phone hasn't had major issues or bugs upon its release. However, a small number of folks, namely in South America, whose carriers primarily use Band 4. Some other reports of the same issue have come from Telus and Bell customers in Canada, despite these reports, there haven't been any issues reported from the US. What most of the reports had in common was the reliance on Band 4 to connect to LTE. The Pixels affected were not able to connect to the LTE network and the connection would fall back to HSPA+. The Google Product Forum was filled with replies and gets pretty...
Source: http://www.gsmarena.com/there_are_some_reports_of_pixel_users_with_lte_issues-news-21552.php