I've never heard of a 4-6 hour evaluation before. 1.5 hour max. Whether it's good or bad? It depends on the results. It sounds like they're finally taking you seriously and thus the long evaluation. If the VA is willing to put you through a 4-6 hour evaluation then they are taking your condition very seriously. In my humble, non-expert opinion, I'd say be honest and not minimize your symptoms and you should be ok. But other more experienced people may have more detailed advice. Personally, I'd consider this an opportunity to let yourself be heard and go for a possible increased rating, if it's called for.