Vista had a difficult birth. Microsoft usually releases new versions of Windows in the Autumn, as this is the busiest time of the year for new PC sales. But new computers with Vista pre-installed went on sale at the end of January, normally a quiet time following the New Year sales. Retailers were not impressed with the timing, particularly if they had old stock to sell.
Vista immediately gained a reputation for poor performance, as it seemed to have more demanding system requirements than Windows XP, so much so that Microsoft continued to allow XP to be sold on low-end laptops for several years thereafter, particularly on the new netbooks that were then coming into fashion. The problem was that many cheap computers were simply under-specified with some laptops, for example, being sold with just 512MB RAM (yes, I know, mobile phones have more than that these days). Stuff such a laptop with a top-heavy anti-virus program and the junk that manufacturers cannot resist installing and it was a recipe for disaster. In fact, subsequent testing revealed that on a correctly specified computer Vista would usually outperform Windows XP, but by then the damage was done.
I recently had to revitalise some Windows Vista laptops - quite unusual, can't immediately recall the last time I had to do this! It was quite an interesting experience. For instance, the customer wanted the latest version of Internet Explorer (10) installed, but it is not available for Vista so it had to be Internet Explorer 9 instead. This wouldn't install until Vista Service Pack 2 was installed first, plus it then needed another important update applying. About 1/2 dozen reboots later and it was running (in contrast, Chrome and Firefox don't have these sort of restrictions, which seem to be imposed by Microsoft for marketing rather than good technical reasons). There were several other popular programs that wouldn't run either, including Office 2013.
In some ways it was sad to see how poorly Vista is being treated in its old age. Whilst never a fan, I have to state that I never encountered a single problem on a computer that could reasonably be attributed to Vista as such. Strictly speaking, the far more successful and acclaimed Windows 7 is really only Vista with a lick of paint and a few tweaks - think of it as Vista 2. Don't believe me? Bring up a command prompt on the two systems and type VER to display the real Windows version number...