with the pads (specially the senseo branded ones), the best I managed was something about as strong as dishwater (with foam on top). needed to play with the volume and strength settings, where only one combination gave something resembling filter coffee (with foam on top).
mine broke in the end. flappy lever thing on the lid jammed, and when I used a bit of brute force to open it, the senseo machine snapped in half.
with the refillable thingy and double size holder, and coffee of your choice, it is possible to get an acceptably dark and rich coffee, but it takes away all of the convenience and makes it more inconvenient than an old style coffee machine.
edit: all of the “generic” pads that you can find in the supermarket, will fit, even if many are fractionally different shape/size. oh and damp the pad before sticking it in the machine helps a tiny bit too.