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* Full support for push email, calendar, and contact sync when working with a variety of Microsoft Exchange Servers is not included in the currently shipped Android operating system.[60] Third party applications with some exchange sync support, such as TouchDown,[61] K-9 Mail[62] and Moxier Mail,[63] are available from the Android Market though users are charged additionally for them and these applications do not integrate with the phone's built-in calendar and contact applications. Full exchange synch is NOT available, unlike on the iPhone, Windows Mobile, Blackberry or other smartphone operating systems, making the platform unattractive for those business users who still use MS-Exchange.
* The Nexus One reportedly had problems with 3G connectivity and touchscreen at launch.[64] Updates have since been issued for the operating system, including the addition of multi-touch capabilities in the Android web browser and Google Maps functions. While the updates have reportedly also somewhat improved 3G connectivity, it is unclear if user complaints are the result of a deficiency with the device or the carrier networks' 3G coverage.
* At launch, Google only provided support through its online services, and customers could only ask and receive help by email.[65] On February 8, 2010, Google launched a Nexus One order support line.[66][67]
* Goldman Sachs slashed their estimates for sales of the phone in 2010 by 70% due to the half-hearted marketing efforts by carriers.[68]
* The Nexus One does not allow the saving attachments or sending attachments, except for photo (and with a workaround music) files, via the built in email and gmail applications.
* The Nexus One has only limited copy and paste functionality in both email and gmail applications, as it is not possible to copy and paste text from received emails.
source: wikipedia - nexus one