I have stayed there couple of times already. Once right after the soft launch and now last weekend after the official launch at 9th.

Both times the hotel was not that full. I recall EL desk mentioning that only 55 rooms occupied (from 200+) last weekend. Probably due to that both times as a HHD I was lucky enough to get a King Deluxe one bedroom suite and a late checkout (2-3PM). The VIP welcome gift provided was either chocolates or a fruit basket with a water bottle and a 5cl Vana Tallinn for avec.
The rooms in 9th and 4th floors were one of the best ones I have ever stayed. Modern, with great views even from the lower floor and practical. Seems the sofa in the living room is not a bed sofa (I cannot imagine why?) so a extra bed has to be ordered if extra accommodation is required.

The spa is nice with a whirlpool, larger pool (1,2m deep), steam sauna and a normal sauna with a large made in Finland IKI stove and a relaxation room. They had some kiwi, lemon and lime water available there but they all were warm and due to that the kiwi water for example was undrinkable. Though there is a (non drinkable, meant for cooling off in / after sauna) ice machine near by from where the cooler portion of the containers could be filled up by the staff.
The sun terrace with a garden accessible from the spa would be great with a nice weather and I hope the bar will be opened there also when the hotel has more guests.

The very nicely decorated large Executive lounge in the 11th floor was a disappointment by it's offerings.
During the day time only some fruits, muesli bars and nuts were provided with a Jura coffee machine and sodas.
Officially from 5PM to 7PM (actually about 5:30PM to 7:30PM) they opened the lock for the door of the cold beer, provided red and white wine, 3yr Havana Club rum, Beefeater Gin and some vodka.
First time I stayed they had a limited selection of warm small pizza style canapés with cold meat offerings which ran out even in almost empty EL and on the second time they had only three cold offerings. Small smoked salmon fillets in a small glass, dark bread cubes and raspberry dessert.

The breakfast is very typical for Hilton with a cooked-to-order station. Many of the items ran out both times and the service was still slow as they were still learning to operate the hotel.

The location was convinient for me when arriving from D-terminal though not as central related to old town and other sights in Tallinn as some hotels.

Although the staff is still being trained and service there including recoding the keys for late checkout had issues both times I stayed the service was exceptionally polite and friendly. Everyone tried to do their best and all complaints were corrected asap. I already gave some polite direct feedback with a smile while I was staying there and planning to write some more to the hotel if I find the time for it.

Overall I had very pleasant stays and will visit the hotel again this summer and would recommend the new property.

Some photos can be found from:
https://1drv.ms/f/s!AuDpLlCmo-fHkd9RchV0nBnKYzrN6A