After hearing such rave reviews on Chowhound (and Citysearch) regarding Thalassa, I finally decided to try it this weekend. It was, unfortunately, disappointing or at least not what we expected. Here are my comments:
Thalassa offers a variety of unusual fishes, and you order them by the pound. My big complaint about this system is that you have to get at least a 1 lb order of these fish, and some of the fish only comes in 2 lbs or more. Actually, at least this weekend, only 3 of the fishes on the list came in 1 lb offerings; you had to order at least 2 lbs of everything else. Not realizing this at first, I initially asked for one of the fishes that had a 2 lb requirement, and when I told the waitress that I'd rather have a 1 lb fish, she tried to convince me to stay with the 2 lb one, saying that it really wasn't that much. I refused and switched to one of the 1 lb fishes. She then tried to sell me on an appetizer on top of that, telling me that 1 lb of fish wouldn't be much, but again I refused.
The fish I had was the Royal Dorado, and it was delicious. However, the 1 lb order was huge. So basically, if I had gotten an appetizer on top of it, or had a 2 lb order of fish, it would have been WAY too much. In short, I am not sure what the waitress was thinking. Maybe 2 lbs would be appropriate for a big guy, but I'm a 5'3" female, and while appetite doesn't always correspond to one's size, I wound up feeling like the waitress had just been trying to get me to over-order.
My boyfriend had the swordfish entree (this isn't part of the fish by the pound list, but on a separate list of entrees), and it was bland and tasteless, possibly one of the worst swordfish orders that either of us have ever had.
Thalassa is pricey. I didn't know anything about the cost before going, since no one seemed to comment on it, although I figured that since it's in Tribeca, it wouldn't be cheap. Still, all of the entrees were around $25 and the fish by the pound ranged from $22-28 per pound. Now, can you imagine if I had ordered 2lbs of a $28/lb fish? It would have been overkill, both in terms of amount and cost.
I am not an expert on Greek food, but it seems to me like Thalassa offers primarily Greek-inspired seafood, as opposed to authentic Greek food. Or rather, if you're looking for more typical Greek dishes (e.g. mezze, etc.) to accompany the seafood, you won't find it there. Go to Thalassa for seafood, not for other Greek specialties.
In short, I'd be hesitant to go back to Thalassa, unless perhaps it was on someone else's tab. While my order was delicious (and I really liked the olive bread they serve, and my boyfriend was happy with their cheese appetizer), the fact that my boyfriend's swordfish was so disappointing makes me wonder about quality control. Also, given that I know that I'd be limited in my choices of fish because I don't want to order more than a pound is a concern. I guess if you can agree to share a 2 lb order with someone (or if you have an enormous appetite), then maybe it's worthwhile. I would say, though, that we were happier with the meal we had at Molyvos.