I owned a pre facelift C30 2.0D for 18 months so I may be able to answer some of your questions.
The car was ideal for my needs when I had it. If you are looking for a practical hatchback this is probably not the car for you. There are only 4 seats and access to the rear ones is not that easy. Also while the boot is quite big, it can be hard to get large objects in it due to the size and shape of the rear hatch. While the car only has 4 seats they are Volvo seats which means they are excellent. All of the 4 seats in the car are the same (so the rear seats are the same shape as the front seats) and in this class of car I don't think you will find a more comfortable place to sit.
The build quality of the cars is very good. To me it felt well put together (More so that my current BMW z4) but some of the plastics that are out of initial sight are a bit cheap. While the styling is a bit bland it does have some interesting touches with the floating dash and black and white seats (these look the best imo). The one thing I did find was everything is easy to use it the car. Cruise control and stereo control are all on the steering wheel which means you hardly ever have to take you hands off the wheel and if you do all of the main thing you want to change are on the 4 dials on the dash.
The 2.0D engine in my car was, in my opinion, very good. While it wasn't the most powerful it felt quite brisk. The power delivery meant that changing gear was not really necessary for overtaking. I covered about 200 miles a week of mostly A and B road rush hour traffic and would average 45 mpg. Motorway runs would see me average high 50s. The cars handling was OK. It is quite prone to under-steer when pushed. This improved when I swapped the standard 7.5” wheels for some 8” wide ones. With the post face lift I believe Volvo changed the engines and they are not not as good. As for having the 1.6D I'm not to sure how well this engine would go with the car as it is quite heavy. I guess this will come down to personal taste/needs but thing you would have to drive one to see how it was. Another thing to note is that volvo servicing can be a bit more expensive than say for a Ford, Honda, Vauxhall etc.
The car overall is quite a marmite car. You are either going to love it or hate it. I personally enjoyed my 18 moths of ownership and if I had to move back to hatchback it would defiantly be on my list.
If you have any questions let me know