i've operated many, many dells throughout the years. although i always piece together my desktops, i decided on a dell for my home laptop -- the only one that i've personally owned.
aside from a few things that i don't like -- that comes with the territory of buying pre-built PCs -- i think they are excellent machines, especially for the price.
i think many people just like to jump on the bandwagon and bash them, without any solid reasons.