The hotel itself is great, I was here for a week on a business trip. Jim, the spa, the pool - there is, but it was not up to that. Breakfast and lunch are standard for five-star hotels. I had dinner in cafes nearby, so I can't rate the hotel restaurant.
In terms of getting somewhere, the hotel is inconveniently located, it takes 15-20 minutes to walk to the nearest metro along not very convenient sidewalks. The free hotel shuttle bus that runs to Syntagma Square helped out. And there you will find shops, and the subway, and buses, and attractions.
By the way, don't get fooled by the park type sign next to the hotel along the marina. It's just a gravel playground, without any trees.