GMAT Strategy

Hi there,
I just sat the GMAT the other day, it was a lot harder than expected, I was getting fairly decent marks in my prep, but my result on the day was quite poor. Could people chime in with what they believe is the best prep company. I went a bit mad a was buying bits of this and that but is there one company that is really really good? I heard the economist prep is good, in that as you go through the questions it highlights weak points. Is it any good? I'd really appreciate the feedback before going back to battle with this exam. Sentence correction is by far my weakest area in the verbal. And I need a huge improvement in the quantitative sections.
Thanks, Tom

I would say that 'best' is a relative term. There are a lot of advantages to different company. If you are looking for an online platform, the Economist is very good. However, if you are going to require someone to help keep your studies on track, you might want to consider in person options.