The Astra is a great little car, I have owned 2 of the 1.2's and a 1.3. The 1.2 is a quicker motor, quicker 0-60 because you don't have to worry about loads of gear changing (4 speed), good for around 105-110 mph on a long road (MkII Astra's still have a better drag coefficient than most new cars (0.32).
The 1.2 in standard form, unlike Nova 1.2 engines has a Webber carb that is easily tuned, it also has uprated valve timing and power when you need it.
Its rivals should not be seen as Pug 405's, but Polo's, Fiesta's and Rscorts.
Practicality is fantastic, 2 mountain bikes go in the back with the wheels on, components are the cheapest you can buy, £5 for front brake pads!
If you want a car that is cheap to buy and run, this is it.
I got 110mph in the rain on the M180 out of the 1987 version of the 1.3 engine. Didn't go any faster cause the Humberside police have a habit of hiding speed cameras and traps behind trees. and I was near my exit.
Anybody who says a Pug can outrun an Opel (Vauxhall) has not seen my baby, 1.6 '88 5 speed CD, 2.0, mags, looks like a total babe and goes like snot, so Pugs come to S.A. and have a go.
115mph? Don't be fooled by speedos. Timed over measured distances, mine says 82 at 70 and 100 at 80! Nevertheless mine can certainly move. And at 170000 miles the engine is as quiet and clean as new (dismantled for decoke just a fortnight ago).
Mechanical problems? Nothing specific or more than you would expect with any car. Carburettor fills with water in the winter but is very easily cleaned.
Door locks are hopeless - fit an immobiliser.
Overall - best car I've ever had.