Man that sucks.
If you really have that much lag you have a problem. Otherwise, ehh. I've been driving turbo fours since the original VW 1.8t in the B5 passat....200k on that, and another 190k on the last gen 2.0T from VW both of which are the standard bearers/originators for the current turbo 4 crop of engines. Put probably 8k on the Ford and GM engines on rentals. This blows them away in terms of turbo lag, and ability to rev quickly. But there is lag.
Traffic, use the cruise it has probably the best programming in terms of smooth braking of any major manufacturer, and will go to full stop and bring you back up. If yours is not smooth...go to dealer and get it checked. Cause seriously I have at least 1k miles on mine between downtown Los Angeles and Palm Springs in rush hour traffic and it is unreal smooth, far better than my brother-in-law's XC90. Really it sounds like you have having a problem with your tranny/engine computer systems.
The parking sensor beep sucks.
The volume of warning beeps can be set in menu under settings, it might not be able to draw on it, but the infotainment system does allow you to adjust many of the settings.
Interior..funny I look at the new Porsche's and see the same dash plastics and switch gear as a 20k Jetta....BMW, Land Rover, Jag...hollow cheap thin plastics, Audi, same thing. Then dont get me started on the 10 to 15 different textures, various shades of colors that vary slightly from one plastic piece to the next. Most interiors (especially GM) make my OCD go into overtime. The Alfa? Nope..all the colors and textures match..awesome.
Touchscreen...rather not have it. Rather not have an infortainment system, rather have the ability to install it all myself, but no one will let me do a stereo delete option anymore.
IMO all the factory upgraded stereos are junk. Yes I have heard most of them. Have you heard a 20k aftermarket system with 1500 watts of pure class A amplification from Brax/Helix running Morel 3 way speakers with handmade custom crossovers, 2 8" Jl audio w7's up front and a single 12 in the trunk? All setup with custom eq curves, phase and time correction? Everything else sucks.......but the HK is alright once you get used to slumming it.
Tranny seems smooth to me, but what do I know? After I lemoned out my VW Eos V6 because the DSG broke the 2,4,6 cogs repeatedly under hard driving (and had to remove that amazing stereo system), I have been manual only for the last 8 years. However the Stelvio shifts very similarly the BMW's and MBZ's my friend's drive, and smoother than I remember my '05 Land Rover LR3 being. It is more positive, however it is programmed to be similar to a sequential, which is more positive feeling due to the presence of an actual clutch plate sooo....
However I will say the brakes, tranny and steering all took some adjustment to how I drive in order to get everything smooth. Things were jerky until I changed my habits on how I operate the controls. Some people may think that is a problem with the car, however IMO it is not.
Other than the Stelvio my favorite car has been the '07 Porsche Boxster I put 50k on in 4 years. I had to change alot about how I drove to get the most out of the Porsche, smoothness on the steering gas and brakes into, and out of, corners became incredibly important since the mid-engine layout rotates differetly through corners than a regular front engine car. I had to change how I entered and steered through the corner or I found myself missing the apex. Never thought that was a problem with the car....my smoothness issues with the Stelvio have been dealt with the same way. But that is me and thankfully we are all different.
Whatever your opinion is very valid in your life, and it sucks you hate your Stelvio.
Sorry, I had an 03 BMW 330CI once felt the same way about...always wanted a BMW till I bought one..sold in in 6 months. Too heavy feeling, boring to drive under 100, tailights and CD player kept braking..sucked.
Hope you can get into something you like better before your lease is up. You realize a lease can be traded in like any other car....