I work for Hansard, and last year we started doing Regional Committees at various sites in the UK instead of in the House. We needed a portable, reliable recording device that was sensitive enough to be able to pick up voices from a variety of directions with no distortion or loss of quality.
We chose these units. They're not the cheapest but they are easy to use and very good quality. The files are stored on the SDHC card, and are easy to transfer.
There's value here, as you also get a tripod (nice, but not essential), and a 16gb card (worth about £24). The unit itself isn't cheap, but if you want a device to rely on, this is it.
Make sure you get some AA batteries to go with your order.