After the "yo' mama is so fat..." kind of messages, I'll try to get back on topic
Being objective, Wester is not wrong. The whole way the 159 project was conceived and managed was botched to say the least.
It is a beautiful car, one that makes you turn around twice every time you walk away from it, it had category-beating levels of grip when it came out (even the German press had to concede), it's still very pleasant to drive and in general is a better car than most people think.
Without going into the merits of the JTS engines (which do not nearly deserve all the bad mouthing people give them), or the perceived weight issues (the 4-cylinders JTSs weigh in at 1480kg, far away from the 1.7 tonnes figures flung around; A contemporary A4 2.0 TFSI was 1450kg, and nobody had an issue about it), there have been indeed a number of issues with the project:
The cooperation with GM was a huge own goal: for a brand that has been badmouthed for years as being "rebadged FIATs", the last thing you want is for people to say "they're just OPEL under the skin". And that's exactly what happened;
Then the horrible gearboxes; especially the M32, they're as refined as a bag of spanners
. Leaving the bearing issues aside (which alone should have told FIAT/Alfa to go look somewhere else), they're slow, notchy and generally unpleasant. Not suitable at all for a sporty saloon, whereas both the second gen 155 and the 156 had much quicker, fingertip-operable 'boxes;
However, above all else the market placement of the 159 has been an horribly butchered job. Ask around and you'll find most non-motor savvy people think it's the successor of the 166, not the 156
. They had a warning about this when a press-only event in Italy generated the same kind of reaction - most of the invited journalists thought it was more of an E-segment flagship, than a D-segment sports saloon, yet they did nothing to address the issue.
In the best case scenario, this put the 159 in a segment of her own - a limbo between D and E that doesn't really exist; People I know have been put off buying one as they deemed it too big for their needs, and ended up with a 3-Series instead.
But more often than not, most people ended up comparing it with more upmarket E-segment offerings from other brands, a scenario in which the 159 was never really meant to compete. To this day, I am often asked "this replaced the 166, right?".