This is a guardedly more positive review than some here I've seen; I thought it was worth sharing my experiences in trying to beat the Senseo into making good coffee.
For the record, my standard of "good" coffee is freshly roasted by a local coffee roaster (Barefoot Coffee, in my area) or even by me (I own a Caffe Rosto), ground just before brewing in a French press. Why in the world did I even get a Senseo, you may ask? The office. My office's coffee is terrible. Bringing in a grinder would not win friends in the cubicles, though, and while I've tried grinding enough for a couple days before I go into work and using a single-cup brewer (I have both a plastic Filtropa-style cone holder and a Swissgold brewer, both that go right on the mug), it's a hassle. I leave things at the office when I should bring them home and vice-versa. I've ended up buying coffee on the way into work, which defeats the purpose of this all.
You probably already know the scoop by now: the Senseo uses pre-ground filter packs, and brews an 8-ounce mug under moderate pressure, the effect being something between normal brewed coffee and a cafe crema. Using it is quite straightforward--you add water to a removable water-tank in the back, put the pod in a pod-holder in the top, and press the magic button.
The big problem, as has been noted by other reviewers, is that the coffee is terrible. Your first cup will look very foamy and pretty, and taste... well, foamy. And watery. When I had mine, I thought, "Great, I've paid $70 to have my very own gas station coffee, with added foaming agents!"
The problem, though, isn't the machine, it's the coffee. The only readily available pods are the Senseo-branded ones, using Douwe Egberts' coffee. They make a great deal of noise about the legacy of this company, but hey, Folgers has a long history, too. In fact, the Yuban-branded pods from Maxwell House (the only other pods I could find in grocery stores) are slightly better, and that's not to say they're good. It's not the Senseo's fault it produces swill when this is what you're putting into it--brew this stuff in a vacuum pot and you're going to get swill, too.
However, there are other alternatives via mail-order. So far I've only tried products from BetterPods, which makes larger pods (you need just one for a mug, rather than two), offers a variety of coffees that are closer to what you'd expect from a coffee store--i.e., "breakfast blend," Costa Rican, Sumatran and so on, rather than the unhelpful "light roast," "medium roast" and "dark roast" of Senseo's brand--and claims to individually pack each one right after grinding.
And, so far, they really *are* better. Nobody's going to mistake this for fine French press coffee, granted, but after the Senseo and Yuban attempts, it's a revelation. These are cups of coffee I'm actually going to finish, as opposed to stare at mournfully.
There are other companies making pod coffee, most of whom I haven't heard of before (Baronet coffee?) and the occasional inexplicable one (Wolfgang Puck apparently has a full line of pods). I doubt I'll be trying all of them, but I'll definitely give a few others a run.
I've noticed a few tricks help the machine: after putting the pod in the pod holder, soak it with a little hot water before you brew it. Stop the machine before it gets to a full eight ounces (seven is close enough, and the last is going to be the abominable foam). Stir the coffee before serving it.
And most importantly, get pods for it that don't suck.