I've had the Topfield (160gb version) for around 18 months, and I can no longer live without it; I rarely watch appointment TV anymore. The ability to use the 7-Day EPG to record up-coming programmes at the touch of a button, and easily set it to record each week, weekday, or daily with just a couple of extra buttons is so convenient. Plus, the pause, bookmark and rewind facilities for when I am watching live TV are major plus points. It holds loads of programmes, has the ability to create sub-folders so each family member can have their own. There's the 30-second-skip function, for zipping through the ads, and the build quality is also excellent.
Previous gripes with the interface have been resolved with the latest firmware version (released in July), which adds to its ease of use and fixes any issues I've ever had.
Other major plus points are the community of people who own the box, and a web site where easy downloads of firmware are available (with idiot proof instructions). It does require a PC/Mac to use this aspect, but straight out of the box, it's still a marvellous piece of kit.
There's some noise when the unit's recording and the TV's not on to mask it, but it's not 'loud'.