Positives: Good sound and comfortable to wear. The fact that the headphones take two standard rechargeable AAA batteries - rather than dedicated Sennheiser battery packs - means that the batteries can be cheaply and easily replaced when they finally wear out, and that you can switch to a charged set if the ones in the phones run flat. The on-the-base charging is very neat and works well.
Negatives: The controls are not very user-friendly (the volume and tuning are fiddly, identical and next to one another, so are easily confused), and the range ("up to 150m") is optimistic, though good enough. More importantly, the headphones will fall off your head at the slightest provocation. They're fine for sitting in an armchair or at a desk, but do anything more than walk sedately around and they make a break for it. Don't even think about bopping. Or washing up, unless you want to rescue the phones from the sink. Actually, there is a solution, if you don't mind being a source of amusement to everyone around you: put one of those infinitely adjustable web straps with a spring-clamp buckle round your forehead (the stripey straps made by Arno and sold in camping shops, for example). Then you can bop, wash up, do the John McEnroe look, and give endless fun to those around you.