HI All,
I find here many people (working/non working) not sure as to join a coaching or not or which one to choose from the herd. I myself was in a dilemma exactly an year back and chose an institute after lot of thinking. But I would like to bring some points which I expereinced in my journey to CAT all this while.
Though I am "still" not an IIM cracker but I will be one day but I think that I might be able to clear some of the apprehensions of people (working/non working) about coaching clases.
For working proffessionals-
Dearies, it takes a lot of strength and courage for preparing for CAT after 10-12 hrs of gruesome office work and I salute everyone of you for managing it so well. (Even I am amongst you but I struggle

) For people of your stature, it would be quite apt to go for a weekend course in an institute which you thing best capitalises in your weak areas amongst QA,VA,DI. Its not essential that engineers (for eg) always have good QA skills. And for that matter its really humane to acknowledge that and get into the killing mode for the same. The same goes for other domain experts also.
Most of the organisations do have SAT-SUN off and these two days are the ones you should target majorly for your preparations. Attending 3-4 hrs of coaching classes and then your own studies of 4-5 hrs on these two days will be enough and suffecient.
For non working people/fresh passouts-
Dudes/dudettes, you are possibly in a better shoe than us to have the time and energy to make the kill. It might be easier for you to give more no. of hours to preparation and come up with flying colors after an year.
Reagrding coaching classes -
Personally I feel IMS test papers are of good quality/standard (just like CAT). The VA part is really good in IMS materials/tests. QA is also of good quality (atleast I found it good). And DI-LR is on an easier side but still suffice for CAT and other exams.
CL has grown tremendously and their professionlalism is great. They come up with good mix of tough and easy questions (which actually is the real case in CAT).
TIME- I find their AIMCATS to be of higher standard than actually needed for CAT specially DI part. Though the test takers are more but the level of paper is also something to be looked upon. I salute those who manage 95+ in AIMCATS.
Its may-end and still 6 months to go for CAT. Daily 3-4 hours of sincere effort should make sail through.
Whichever coaching you choose, it boils down on how hard you work and analyse your mistakes.
All this is my opinion and people do have different point of views.
BEST OF LUCK TO ALL,
Mrinal