If you are looking for 5 star comfort and luxury, the Eden is not for you. If you want a modest, well run and spotlessly clean hotel, it will meet your needs. My wife and I holidayed there during the last week of September and had a really pleasant stay. The food was good, not brilliant but good and more than adequate. And the wines aren't bad either - quite a nice surprise, in fact.
The staff were efficient and helpful (although, as seems to be the Croatian habit, you need to ask but then you are served promptly and with pleasure).
The Eden Hotel has a good size outdoor pool and a nice heated indoor pool (with adjoining spa and therapy rooms).
The hotel is set within its own grounds on the edge of a coastal parkland and a healthy 20 minute walk from the ton square. So if you like an after dinner stroll, you can amble along the promenade taking in the vista across the harbour and bay along the way.
Likewise, if you like walking along beautiful coastal pathways with lots of bathing points along the way, your needs will be met. You can also hire bicycles at the hotel to ride around the coastal parkland.
As for Rovinj itself, it is a charming little town with a number of modest attractions. Shopping is as you might expect in a town with a winter population of about 10,000, however there are 87 restaurants to make up for any shortcomings on the retail side.
A number of excursions are available (including to Venice and Zagreb). Having visited both in the past, we confined ourselves to the Istrian peninsula.
Bad points? None that I can recall. Before booking, we read the Trip Advisor reviews and having experienced the place can say we were comfortable, well fed and content. Some of the less charmed reporters must be miserable or unlucky or both. Oh, yes that reminds me one poor point. The restaurant only serves bottled water for which you have to pay, which I felt was a poor show and just encouraged me to drink more wine than perhaps I should.
The Eden Hotel is not a 5 star establishment but I would be more than happy to stay there again, And again!