I recently stayed here for an event that was taking place at the GWCC. While not as convenient as the Omni that is practically attached to the GWCC, the HGI is a great alternative (and a HHonors property). The Embassy Suites is a couple blocks closer, but I see no reason to pay the extra to stay there when the HGI provides great accommodations, a wonderful cooked-to-order breakfast, and (from part of the hotel) great views of the city.
Easy couple blocks from Centennial Olympic Park, Aquarium, World of Coke, CNN, and plenty to do within walking distance.
If I had a complaint, it would be with the lack of decent airport transportation. The only three options are MARTA (cheap and easy, but quite a walk to the nearest MARTA stop if you've got luggage and/or are traveling super late night or early morning); Shuttle service (Which costs money, but stops running at 9:30pm); or Cab (which is way overpriced, but our only option given late arrival time from ATL).
Also take note that if walking to the GWCC, it can seem a little uncomfortable late at night. Marietta St isn't the warmest of environments. I expect this to improve a fair amount when the College Football Hall of Fame construction is complete.
If back at the GWCC again, I'd most likely stay here if I can get a more affordable transportation option squared away.