After reading all the reviews I could find, I decided to take the risk of getting one of these (I actually got a single handset version, but am adding the review here to keep them together). The operation and function of my single handset is as easy as pie... especially after READING THE MANUAL!! For those, like me, who would like to see more info before buying (the manual does not appear to be available online) here's some more detail:
Reception seems to be fine - I don't know if it varies with more handsets. There is an ECO mode which reduces base transmission power - I suppose if set to 'on' by mistake (not easily done, unless pressing buttons randomly in an attempt to avoid having to read the manual) it could result in disappointing reception. As with any transmitting device, it needs to be placed away from other electrical devices to maximise quality.
The base station has a 2 x 15 mm LED which shows green, amber, red or nothing, depending on location of handset and whether answer machine is on/off. The LED flashes when you have messages. The handset needs to be placed carefully on the base station if fixed on the wall, otherwise it tends to fall off (as observed by another reviewer) - but if placed back properly, it does latch onto the small hook adequately and does charge properly.
The white-on-black handset display is basic/blocky, but really clear - it isn't a mobile phone, after all.
The answer machine is EASY to access - okay, not as easy as having a separate machine with a single press "Play" button. But all you have to do is press 'up, up, ok, ok' to play messages - what does it take, 2 seconds? And yes - you CAN easily delete messages one at a time as you listen to them (as C.Kanu suggests - RTFM!) It is also easy to record your own outgoing message, which plays very loud & clear. You can choose ring delay of 2-9 or 'toll saver' (when accessing it remote, this option answers after 2 rings if there are new messages, else after 4 rings).
Ring volume can be set from 0 (off) to 5 (pretty loud); the external speaker in the back of the handset can be varied from 1-5 whilst in use. The 10 ringtones are funky - not iPod quality, but good old-fashioned polyphonics: 4 basic ringtones, 4 classical music representations and 2 more modern ones.
Names/numbers are easy to add to the 100-entry phonebook. You DON'T have to scroll through them all to find what you want - whenever accessing the phone book you can use the number pad to represent A-Z and it skips to that section. Names can be put into 1-3 groups (or none) and if you have caller recognition you can set the phone to play a different ringtone for each group.
The buttons have good positive action ("clicky" in the view of some) which means you are unlikely to press a button by mistake.
Top level menu:
phonebook, clock/alarm, personal settings, advanced settings, answ machine
Some other options not already mentioned above:
auto pick-up on/off (uses handsfree), auto hang-up on/off, babysit mode,
outgoing call barring, auto prefix, 3-way conference calls.
Size: handset is approx 165 x 50 x 35 mm - smaller & neater than I expected.