There was only once that I had a tiramisù in a restaurant here in Portugal that I liked (they tend to skip the marsala wine), however since I've never been to Italy, I cannot compare.
I suppose that the top restaurants, namely those in hotels, must do it well, but I don't frequent them.
Some years ago I found the Bontà Divina brand in the supermarket and when I saw the tiramisù, I had to give it a try.
I must say that I'm always suspicious about buying desserts that are not home-made, but after reading the ingredients that include mascarpone cheese from Alto Adige, sicilian DOC marsala wine and coffeee, I thought that it could be a good option.
Like I said before, I've never been to Italy to try the original, but I can tell you my option resulted quite positive.
The product is well presented and its degustation is pleasing, with a special touch given by the marsala wine.