My wife, two children and I stayed at the Green Park Hotel for 3 nights in July 2008.
First, the bad things about the hotel: The room was unbelievably small, with one double bed and a bunk bed, and no walking space whatsoever. I requested for a larger room at the front desk, but they didnt have any available. There is no room service to speak of. The hotel is about 15 minutes walk from the waterfront.
Now, the good things about this hotel: The room rates are reasonable, and the breakfast was quite decent. The manager lady was always very helpful, and so was her husband, who was always willing to drop us off at the train station (from where you can catch shuttle buses to either Gardaland or Aquapark). There were quite a few things to do for the kids, like an outdoor pool, table-tennis, mini-soccer, and Playstation. They also sold Gardaland tickets at cheaper prices.
In a nutshell, its not a bad hotel at all, and you can consider staying there if better options are not available. The Bella Italia campsite looked great, but unfortunately we we didnt know about it until we were already there. Maybe I'll try it out next time!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC