False.
That said, dont do a cadetship. You miss out on the uni lifestyle, the new friends, the life experiences and to top it off you end up with crap marks and mundane work (you get given the crappest tasks because you are the cheapest for the firm).
To address your generalisations with my personal experiences....
I've made many friends from my cadet intake (as well as the broader cadet group, graduate group).. Working at the same place and attending uni together is a rather binding thing to have in common with someone else.
I can't even begin to imagine where you're coming from when you talk about life experiences. My life experience is that during a year and a half out of highschool I've worked with hundreds of different people on dozens of different clients. I've had a taste of lifestyle most uni students are naive to until they've graduated.
I know what's coming and I've developed a lot of confidence and many professional behaviors that normal uni students lack, which I see every few months when a batch of random vaccies or interns show up fresh.
My uni marks are great and I've overloaded the whole time. The work I do is on the same level as graduates in their 2nd year of work. The thing that disappoints many people I've found is that cadets perform the same work more qualified people do but are paid less.
Now that I've satisfied my taste for work I plan to enjoy my remaining 12-months of full-time uni and travel the world for 6 months with the money I've saved from working, knowing that I've got a job down the track should I wish to take it (N.B. more relevant than ever a job that is relatively safer in the current environment)
I just think there's no need to be so one-sided. I'll tell anyone that asks me about both sides of the coin. You mentioned you know some people who have had good experiences but I just thought I'd balance it out a bit more ...
In my experience there's three groups of people who drop out of cadetships and subsequently complain about it:
A) People who didn't know what they were getting themselves into
B) People who weren't cut out for it and generally bad at time management
C) People who are more creative/entrepreneurial by nature
In cases A) & B) I say bad luck, in case C) I'd say any form of regimented full-time work is not suited for them... I don't see how B) and C) would be able to flourish in an IB environment that's renowned to be demanding.