I have actually gone the other way, Puma 1.7 to 147 2.0, and i have to say, the Puma is the better drive. It has really direct weighty steering, a brilliant gearbox and the handling is spot on with little roll and a touch lift off oversteer. Reliability seems good too, i have only had faulty abs sensors, which considering i have had it for 2 years and 40 000 miles seems pretty good. The 1.7 engine revs away, and doesnt seem to mind the odd thrashing now and again, and even though it only has 123 bhp the lowish weight makes it feel nippy, i had a wee drag race with me in the Puma and dad in the Alfa and he couldnt drop me, its also fairly economical when driven sensibly, returning 40 mpg easily on a run.
Now the down sides, driving position is TERRIBLE, seat too high, gearknob too far away and steering wheel jammed against my knees as it does not adjust, if you are above 6' you will also have headroom issues, im 6'2 and have to put up with my head being on the roof, the engine lacks low down torque and with the heavy controls (although great for back road bashing) make it quite tiring in traffic, it is also quite noisy at speed and could do with a longer 5th or a 6th gear. The bodywork could be better, you will be doing well to find one without rust on either the rear arches or the sills, and if you do i want to see it!
If you do get one, i doubt you would regret it, the slight discomfort and lack of space is worth it for the drive.
And if you havent seen it before watch this, from top gear 1997 http://uk.youtube.com/watch?v=AvfwYhB5YuI