The IIT-JEE, AIEEE, BITSAT and all other Engineering Entrance Exams are all very over hyped. Must say, even IIT-JEE has stopped being conceptual since the time it started MCQ's. It tests more of your numerical ability than anything else. If you know the right formula to use(and there is normally not much debate on that one) and are good with manipulating numbers you'll get through IIT-JEE. The IIT's rose to great heights in the days when the IIT-JEE paper was really tough to crack and extremely conceptual questions. In these MCQ's it is really easy to substitute the answers and reach the question in atleast 20% of the questions which increases the overall score of everyone. If you know many such back-of-the-hand tricks(and they are there in plenty!!) you will easily score in IIT-JEE.
Also, on the previous topic, I pretty much agree that the criteria for each stream must be decided on a candidates prowess in that field and not in all fields together. For e.g. I am good at programming and have a lot of interest in microprocessor technologies and cryptographical systems. I can do well in Physics and Math but was no good at cramming so lost out on Chemistry since a whole lot of chemistry involves mugging loads of things(Formulae for Physical Chemistry, All of Inorganic Chemistry, and special cases for Organic Chemistry, and every other reaction happens to be a special case of some general law.) So, all thanks to chemistry I couldn't score well in my Entrance Exams. As of date I can perform better than any other CS student in my institute without having attended a single lecture of those courses, but I am not allowed to take that as my Engg. Degree and must study Mechanical cause thats what my marks could BUY for me..