Good morning!
...does anyone know anything about this plane?
What exactly do you want to know? I have flown over 1000 hours on 4-series Cessnas (421,404,414A) and was never very happy with the 414. It handles nicely, but lacks performance. Legally, with full tanks you can only carry one passenger or so, and with a full load of passengers, you won't get anywhere. It really is an aeroplane for a self-flying businessman who does short trips only and never carries more than two or three persons.
Is it good to buy?
Twenty five years ago maybe. Not any more. Too old, too rare. Too many ADs. No spare parts. Too much fuel consumption (AVGAS, now almost 3 Euros per litre in many places!)
what are the differences with a 421?
Mainly the engines. The 421C (Golden Eagle 3) and the 414A (Chancellor) are almost identical, apart from the engines. The 414 has 310hp (IIRC), the 421 has 375. This aircraft requires 375hp to fly properly, especially in case of an engine failure. The engines of the 414 are not geared, therefore the aeroplane is louder inside and out, but on the other hand they are less delicate than the "GiTSOs" of the 421.
Overall: If you want to make a small fortune in aviation ... a C414 is a good starting point
Happy landings
max