What follows is my "take" on 432MHz operation over the years. As with all my ham band operation, I have never been one for large antennas, high power linears and the likes. Most times I operate with 5-10W and frequently with far less. Clearly, if you have a stack of large yagis on a 50m tower and well over 1kW erp you will be able to make contacts over distances I could not imagine and access modes such as EME that simply would not be possible with QRP. What I want to show is that even with a very modest antenna and a few watts (or milliwatts) the band is still capable of great results and enormous fun.
My very first experience on the band was back in the early 1970s when I first came up to Cambridge. Having no equipment for the band I built a passive tripler using a varicap diode and simple down-converter based on a design in VHF Communications magazine. With my homebrew 2m AM transmitter which put out 500mW I was able to achieve 100mW output on 70cms. On receive the passive mixer had about 6-7dB loss, so it was not very sensitive, but it worked. With just a 4 el yagi in my loftspace I made my first tentative contacts with local stations. Greater fun was to be had out portable and in contests the best DX with just 100mW AM and this very small yagi was all the way up to Yorkshire (G3NHE) at around 160kms. In those days a call on ANY evening from a hilltop would guarantee several contacts up to 50kms away even with such low power and simple antennas: activity was high.
In the early 1980s I owned one of the first FM321 70cms synthesised 4W FM transceivers (based on an Australian UHF CB radio) and with this plus an old Jaybeam 48el TV antenna mounted vertically on a pole and turned by hand on the side of the house I was able to work lots of local repeaters and some decent inter-G DX on FM simplex when there was "a bit of a lift on". 70cms has localised lifts every few days and that was part of the magic of the band: one day you could hear just locals and the next (in just one direction maybe) more distant repeaters or simplex stations could be heard or worked. Every day was different. Occasionally the band would be wide open and some super DX could be heard or worked.
In those days I did not have any SSB transmitting gear on the band but I did listen in contests and at other times and well recall hearing an OZ station running 10W SSB to an HB9CV antenna and being a true 59+ signal on a small indoor beam in the bedroom. The band is excellent for tropo DXing, but it is much under-used nowadays.
In more recent years I have done some operation on FM (simplex and via repeaters) from home using my vertical V2000 colinear antenna and occasionally come on SSB using my 2m halo. It is extremely inefficient but does match quite well and has allowed some contacts. Using VX1 and VX2 FM handhelds some interesting QSOs have been had when out portable on clifftops in Devon. I am sure that with my Moxon coathanger yagi (described elsewhere on this site) or a small HB9CV antenna it would be possible to achieve some quite spectacular FM simplex DX using these little radios or similar.
In the last few years I have tried some portable 70cms SSB/CW contest operation using my Moxon 2el yagi and achieved some decent results. At present I use my 2m big-wheel for 70cm SSB. It seems to match pretty well although I have no idea about the polar pattern on 70cm!
Based on my earlier experience I believe a reasonably sited 70cms QRP station should be able to work 60-80kms or more on SSB/CW in flat conditions to similarly equipped stations. Of course, 70cms experiences lots of minor tropo enhancements so if enough stations were active the country would be criss-crossed with QSOs most days. Sadly, activity is now very limited indeed (even when conditions are good) outside of contests and activity nights.
70cms is an excellent band for portable and mountain-topping operation as the antennas are small and lightweight. See for example the SOTA beam for both 2m and 70cms. Another bonus of 70cms is the lack of interference from TVs, SMPSUs and PCs. Compared with the HF and lower VHF bands it is positively quiet.
Finally, don't forget satellites. I have never tried working through these on 70cms but it should be quite possible with a modest station. Many of the many satellite's 70cm beacons are audible on a very simple antenna and receiver.
Beacons are a useful indicator of conditions on any band. 70cms is no exception although several UK beacons appear to be not operational at the present time. Check the beacon list to see what ones should be audible. Sadly there are very few 70cms beacons in the UK currently. It is a pity more use is not made of FT8.
A useful antenna for beacon monitoring would be a big wheel. These omni-directional horizontal polarised antennas have a few dB gain by compressing the vertical lobe. As they "see" in all directions they allow many beacons to be checked quickly. A couple of big wheels stacked can give up to 5dBd gain, which is similar to an HB9CV without the bother of a rotator.
Do give 432MHz SSB or simplex FM a go sometime and if you think you have no suitable antenna then turn to your wife or girlfriend's wardrobe and search out an old coat hanger. Alternatively, a small yagi can readily be made from parts available from the local DIY shop and rotated either by hand or by the smallest of rotators.
If you only come on for the odd contest you will be assured of some fun and who knows you might be persuaded to erect a more permanent beam and rotator and find out what the band is REALLY good for. Even if you can only run a few watts of SSB and a small beam the band has lots to offer especially in the smallest of lifts.