The drip, with a decent brand, was alright. Tap water here isn't the best but I've had much much worse. Still, switching to filtered water made a huge difference.
Math-wise, I'm not sure yet if it's been a good investment. I've used two pods today ($.75ea) and that's been it, so $1.50. Now, I can get a large can of coffee on sale for $7 and that would make me a full pot a day for about 3 weeks so roughly $.33/carafe (4-5 mugs). Cost per day is definitely higher and that's not factoring in the $2/20L of RO water.
I've spent $100 Keurig, $17 reusable k-cup, $32 pods, $29 drawer, $15 RO water (w/deposit) which comes to $193. That's probably as much as I've spent on beer in the last 6 months.
Quality of coffee has gone up. No question. Basically, so long as the Keurig lasts me a long time and I make proper use of the reusable pod, it should pay for itself eventually.