The ambitiousness and scope of these changes, and the abundance of new features earned positive reviews, but Windows Vista was the subject of frequent negative press and significant criticism.

It was originally expected to ship in October 2003 as a minor step between Windows XP and "Blackcomb", which was planned to be the company's next major operating system release.

Gradually, "Longhorn" assimilated many of the important new features and technologies slated for Blackcomb, resulting in the release date being pushed back several times in three years.

For this reason, Longhorn was reset to start work on componentizing the Windows Server 2003 Service Pack 1 codebase, and over time re-incorporating the features that would be intended for an actual operating system release.

[23] Srivastava employed a team of core architects to visually map out the entirety of the Windows operating system, and to proactively work towards a development process that would enforce high levels of code quality, reduce interdependencies between components, and in general, "not make things worse with Vista".

[26] Microsoft co-president Jim Allchin also loved the name, saying that "Vista creates the right imagery for the new product capabilities and inspires the imagination with all the possibilities of what can be done with Windows—making people's passions come alive.

In September of that year, Microsoft started releasing regular Community Technology Previews (CTP) to beta testers from July 2005 to February 2006.

The builds that followed incorporated most of the planned features for the final product, as well as a number of changes to the user interface, based largely on feedback from beta testers.

[57] Another new technology called SuperFetch utilizes machine learning techniques to analyze usage patterns to allow Windows Vista to make intelligent decisions about what content should be present in system memory at any given time.

[59] As part of the redesign of the networking architecture, IPv6 has been fully incorporated into the operating system[60] and a number of performance improvements have been introduced, such as TCP window scaling.

The Heap Manager implements additional features such as integrity checking in order to improve robustness and defend against buffer overflow security exploits, although this comes at the price of breaking backward compatibility with some legacy applications.

User Account Control asks for credentials in a Secure Desktop mode, in which the entire screen is dimmed, and only the authorization window is active and highlighted.

[72][73] Internet Explorer 7's new security and safety features include a phishing filter, IDN with anti-spoofing capabilities, and integration with system-wide parental controls.

BitLocker can work in conjunction with a Trusted Platform Module (TPM) cryptoprocessor (version 1.2) embedded in a computer's motherboard, or with a USB key.

Obfuscation techniques such as address space layout randomization are used to increase the amount of effort required of malware before successful infiltration of a system.

There are also significant new development APIs in the core of the operating system, notably the completely re-designed audio, networking, print, and video interfaces, major changes to the security infrastructure, improvements to the deployment and installation of applications ("ClickOnce" and Windows Installer 4.0), new device driver development model ("Windows Driver Foundation"), Transactional NTFS, mobile computing API advancements (power management, Tablet PC Ink support, SideShow) and major updates to (or complete replacements of) many core subsystems such as Winlogon and CAPI.

[107] Microsoft releases updates such as service packs for its Windows operating systems to add features, address issues, and improve performance and stability.

The synchronized release date of the two operating systems reflected the merging of the workstation and server kernels back into a single code base for the first time since Windows 2000.

[112] A white paper, published by Microsoft on August 29, 2007, outlined the scope and intent of the service pack, identifying three major areas of improvement: reliability and performance, administration experience, and support for newer hardware and standards.

[110] Service Pack 1 introduced support for some new hardware and software standards, notably the exFAT file system,[110] 802.11n wireless networking, IPv6 over VPN connections, and the Secure Socket Tunneling Protocol.

In June 2007, Google claimed that the changes being introduced for SP1 "are a step in the right direction, but they should be improved further to give consumers greater access to alternate desktop search providers".

[149][150] It received generally positive reviews from PC gamers who praised the advantages brought by DirectX 10, which allowed for better gaming performance and more realistic graphics, as well as support for many new capabilities featured in new GPUs.

"[153] In a continuation of his previous assessment, Bright stated that "Vista is not simply XP with a new skin; core parts of the OS have been radically overhauled, and virtually every area has seen significant refinement.

While in 2005 Microsoft claimed "nearly all PCs on the market today will run Windows Vista",[181] the higher requirements of some of the "premium" features, such as the Aero interface, affected many upgraders.

According to the UK newspaper The Times in May 2006, the full set of features "would be available to less than 5 percent of Britain's PC market"; however, this prediction was made several months before Vista was released.

[182] This continuing lack of clarity eventually led to a class action against Microsoft as people found themselves with new computers that were unable to use the new software to its full potential despite the assurance of "Vista Capable" designations.

For example, Mike Nash (Corporate Vice President, Windows Product Management) commented, "I now have a $2,100 e-mail machine" because his laptop lacked an appropriate graphics chip needed for Vista's advanced features.

A majority of users in a poll said that the prices of various Windows Vista editions posted on the Microsoft Canada website in August 2006 make the product too expensive.

One aspect of this is the Protected Video Path, which is designed so that "premium content" from HD DVD or Blu-ray Discs may mandate that the connections between PC components be encrypted.

[191] Peter Gutmann, security researcher and author of the open source cryptlib library, claims that these mechanisms violate fundamental rights of the user (such as fair use), unnecessarily increase the cost of hardware, and make systems less reliable (the "tilt bit" being a particular worry; if triggered, the entire graphic subsystem performs a reset) and vulnerable to denial-of-service attacks.