The bottom line with "experiences with a Dell computer" is that they will be your own. As a "computer guy," I've been repairing Dells as long as I've been a tech, and they're not evil garbage, contrary to what many "computer people" will tell you.
Dell is the same as any other brand: you get what you pay for. Low-end, low cost Dell computers are typically short on features, slow, and not very expandable. But the same thing goes for other brands.
More expensive Dells, like the XPS gaming machines, are quite nice. They easily rank right up there with the nicest systems I've worked on. They generally contain good parts, are powerful, and allow plenty of expansion. The new ones also look really, really good.
There is one thing that I can say about every Dell I've worked on. They are easy to open, take apart, and reinstall new parts (provided you've got the Dell power supply or mainboard on some older ones). Most of them allow you to install things like modems, video cards, DVD-Burners, etc. with ease, usually without even using a tool.
Also, their cases, whether plastic or metal and plastic, tend to be very, very sturdy. I've never had a Dell case come into my shop that's totally trashed. They're much, much sturdier than a lot of the flimsy tin cases smaller PC builders use in their builds.
Another great thing about them is the service tag. When I reformat a Dell, I can get all the drivers I need just by typing the service tag number into their download page. That's a huge bonus for me as a tech. I don't need to know what addon parts they have, it's all on the Dell page that comes up.
My biggest dislike with Dell systems is how their cases are made. One most computers, the little piece of metal at the back (where you plug your keyboard, mouse, speakers, etc.) is removable. That's not how it is on a lot of Dells. What does that mean? Well, when someone brings me one that needs a new mainboard, I can't sell them one off the shelf - it has to be a Dell.
Dell isn't the only company that uses their own type of case that won't fit normal parts - IBM, Compaq, HP, Gateway - they all do it! They do that for a good reason, obviously. If they sell computers for $299, it's totally in their rights to make sure they earn a little extra profit from replacement parts down the road.
From a repairman's standpoint, Dells are just like another other name brand computer I fix. As a consumer, I'd consider buying a Dell for myself, as long as I knew I could get replacement parts anywhere I want down the road - not just from them.