My girlfriend and I stayed at the Milenij Hotel Sv. Jakob in Opatija mid July 2015 for seven nights and the stay was way above our expectations.
Two things made the stay memorable - the friendly and attentive staff and the amazing breakfast buffet.
Everyone at the hotel - from the manager to the front office ladies to the waiters and even the kitchen personal - were both friendly and professional; no question or request was left unanswered.
The other highlight was the breakfast buffet - a huge selection of various cheeses, cold cuts, cream spreads, smoothies, salmon, caviar, etc - and all of this consumed at the beautiful patio - an excellent start of each day. On top, there are about 10 deserts to choose from, my favorite was 'gibanica', a pastry with layers of poppy seed, apple and cottage cheese.
Two minor points of critique: parking is a bit of a challenge and the internet connection is a somewhat flaky.
In summary, we've had a great time and we can definitely recommend this hotel to anyone wishing to have a relaxing stay in a friendly environment.