well from experience in tutoring it most importantly depends on the student....
The strength of the student will determine how they handle 3u or 4u....
However, all in all 4u is definitely not overated....The concepts you are faced with
far more complex(get the pun) than in 3u.....the reason people will find it easier than some
3u topics is because of the type of maths it is testing...Lots of concepts for different topics
are analytical, which involves deep thinking (the underlying principle behind the hard questions)
whereas other questions are more algebra based which most ppl find straightforward...
All 4u topics can there fair share of easy and hard concepts to understand and same with 3u...
but overall the 4u concepts will win everyday....as to the difficulty of questions well all 4u topics
do some have straight forward questions, but every topic in 4u can have nasty questions asked of you....
whereas on average the 3u questions are all straightforward and although they can ask you some really hard 3u questions,
those questions are really part of harder 3u in the 4u course, so in the 3u paper when there is a super hard question it is
more separating the 3u and 4u students, and the really good 3u students who dont do 4u....So you really cant say 4u is overated....