I rebuilt this car, changing it from manual to automatic.
The styling was always controversial and enjoyable. Most describe it as 'ugly'. Not many would notice the smoothed-out creaselines and soft curves more typical of late model cars. Another feature unheard-of in this age bracket is the bonnet trailing edge sweeping up over the wipers. Even the rear lights have a crisp elegance, although the very 70s trim on these cars (the inside of a vinyl cover sported purple vinyl leftovers) has dated the basic shape.
The engine was thrashy and noisy, and not very powerful compared with other two-litre cars.
Reliability was good, and servicing was easy (e.g. pouring oil in, changing filters, setting ignition timing).
There were a number of squeaks and rattles. The entire fascia was 'suspended', meaning it would shake up and down with the engine idling. There were draughts from the cold-air vents in the centre of the dashboard, torturous on long trips. Water leaks into the interior were very common.
The automatic transmission was smooth but lazy, and very fuel-inefficient. Fuel consumption was an average of 22mpg. Top speed was only about 140km/h.
More importantly, the suspension was quirky and not very safe. The stability at high speeds is poor compared with other cars of this age. The ride quality is very stiff and bouncy, usually because the Hydragas units have lost their gas springs. Hydragas is NOT the same as Hydrolastic; the latter uses rubber springs. When the Hydragas goes 'down' in a Princess (or Allegro) it is because the gas spring has leaked away. Pumping in more water (special green fluid) restores the ride height, BUT the pressure (and therefore the pressure of the gas springs) will be higher. This makes the suspension harder, reduces its compliance (because of the rising rate of the gas springs) and therefore upsets the ride quality and roadholding.
That technical lesson should have highlighted the flaws of a conceptually superior system. The remaining steering problems arise from very light power steering (with little 'feel') and totally inadequate front wheel geometry. This causes great tyre squeal even at low cornering speeds; not helped by the wide (175 or 185) tyres on narrow (4.5") rims. This persists even if expensive tyres are used, and sets a big limit on the cornering grip, even more so in wet conditions.
There is good interior space, but limited headroom and 'footroom'. Trim is of a rather low standard. It can be 'tailored' with DIY care but is still fundamentally 'cheap' in its design.
Electrics are comprehensive but depend on only eight fuses. This restricts reliability and quality, e.g. light output is low.
Some aspects of these cars are very thoroughly engineered; for example the cooling system, brakes, and the gas struts supporting the bonnet. As was said at the time, there is "a great car trying to get out".
In many ways they were underrated cars. I don't wish to 'bash' their reputation, which deserves to be better than some other BL models like the Allegro and the Maxi. However I would caution those attracted by the on-paper specs to try the car for real first, and compare with other cars of the same age.