I've only been in the business class lounge in T3, but I'd assume it would be similar to the one in T1. The T3 lounge is fine, if a little impersonal, and very large. From my experience, all Emirates lounges are very similar, though they may vary in size.

I have visited the Marhaba Lounge and didn't think it was worth the entry fee. The main bonus for me relating to lounge access is the availability of showers, and the Marhaba Lounge doesn't have showers. IIRC the selection of food there wasn't great either.