how reliable is this engine ?

anything exept timingbelt and clutch i need to be aware of ?

any common faults ?

Common fault 1: owners check oil when cold.

Maybe the variator, but that shouldnt be an issue as it has been either working long enough to last some more, or been replaced by now.
MAF dying of old age/dirt.
Clutch slave cylinder is common fault, but easy and cheap

Nothing noteworthy like 1.4 cams or 1.2 headgasket.

And then theres the rest common faults of bravo/a/marea chassis.
Trailing arm bearings, rattling rear seat latches...

Since when did a 147 engine have a variator????

Always, you are propably mixing it with VIS (Variable Intake System) on the 155 and 150.

Apart from the rocker gasket and the MAF, is say its Fiats most reliable engine