Me and my fiancee were in this hotel 4 days in July 2011.
The biggest plus is definitely the hotel location, immediately followed by the hospitality and friendliness of staff. The only minus to mention it goes - especially for the Italian situation - very bad coffee at breakfast.
Destination and the hotel we found through SiteTalk Travel (www.sitetalk.com / WillySLO).
Sirmione is a beautiful but very (really) expensive. For example - a large beer (Birra Grande): 7.5 €.

My family and I stayed at the Hotel Mavino at the beginning of October 2010. We came to Sirmione by car. The access of the city is only permitted for residents and hotel guests. When we arrived, our name was already registered on the control office and a sympathetic policeman opened the city gates for us. Sirmione is beautiful and Hotel Mavino is located in the center, in a prime location. The front desk staff was very friendly, giving us all the information we had to know about the city and its stunning surroundings. The room was great, clean, fragrant and well equipped. Parking is a bit far, in the courtyard of an inactive hotel blocks away. But, beyond the tours around Lake Garda, the use of the car is absolutely unnecessary in Sirmione. Moreover, it is worth the walk to the parking lot, because the scenery is breathtaking. The breakfast is satisfactory. We intend to return to Sirmione some day to explore other nearby cities we did not have time to visit. Sure we will choose Hotel Mavino to stay.

When staying in Sirmione I suppose there are two points to consider first - time of year and whether to stay on the old town side of the draw bridge or outside. I imagine visiting Sirmione at the height of the season would be a terrible experience - the streets are narrow and even in October it was fairly busy. the area before the drawbridge is modern and anonomous- you really could be anywhere. However it all changes once you see the Old Fort by the drawbidge - then you are in the delightful old town. Cobbled streets- opening out with views of the lake, many hotels, restaurants, expensive shops, ice creams,old churches etc.
Hotel is at the far end of the old town- so very convenient for the town, ferry , restaurants fort and walks. Its also not very far from the spa and its an easy walk to the the Grotto of Catullo- not to be missed.
We had a second floor room with a balcony and view of the lake - essential and the view was much better than some of the more expensive hotels could offer. The room was simple and very clean. It had a pitched roof, lined with wood. The bathroom was small with one of those stupid showers with no door - so easy to flood!
I guess the bad points centre around aspects of the room. I have already mentioned the bathroom - add to that the pitiful bathroom goodies - basic to say the least - bring your own. the walls are paper thin and the first two nights were greatly distrubed by the person next door snoring - its bad enough with husband snoring - at least I could kick him!!!!! The third night was equally noisey because an Italian man two rooms along had the TV on a full blast resulting people banging on the walls - fortunately the night porter sorted this out.Although the street below was pretty quiet in the evening - with the window open you could hear people talking - didnt bother us. The dining room was on the floor above and we could here the chairs scrapping on the floor for some of the very early breakfasters - again not a real problem. The breakfast - possibly the worst coffee and juice ever encountered- however there was fresh fruit, croissants, ceral, bread, rolls, meat , cheese - and we managed fine - always took some bread rolls to feed the ducks on the lake!!
The ladies on the desk were very friendly and helpful - a request for more pillows was no problem and they were helpful about getting to Verona and dealing with taxis - the only things we asked them about.
For Verona - get a bus from the other side of the drawbridge - the ticket office and post office are right there. The Tourist office had one of the most unhelpful people I have ever come across - so give that a miss! Takes about an hour to get to Verona- we did two city bus tours that day - its a joint ticket with your own headphones which you take on both buses- valid for 24 hours. If you only have time to do one - I recommend the B tour which includes a stop to get out and take photos above the city. You can hop on and off at any of the stops but there are not many buses - so watch the time so you dont miss the bus back to Sirmione. If you want a taxi - its easier to walk to the bust stop area outside the drawbridge and pick up one there than order from your hotel.
Boat trips on the lake are easy - there are some private tours but we just used the ferry - check you times carefully - they dont all come back to Sirmione!
I would probably use this hotel again - the good points - location , view etc outweigh some of the bad ones. But I would be very careful about the time of year- also its an expensive area.I have no idea who the shops are aimed at since if you are flying in on a budget airline to Bergamo - you dont really have much of a luggage allowance.
We used the train to get to Sirmione from Bergamo- straight forward and reasonally cheap - however taxi from the station at Desenzano was 24Euros
dont forget to have an ice cream and spritz aperol

Hotel Mavino is a three star hotel built four years ago, well situated away from the tourist end of Sirmione. The staff are very helpful and friendly. The rooms are well appointed and very clean. The Breakfast Room is in the roof of the hotel and can be cramped with a large group eating all at once but the continental breakfast is good. We were part of a group of 36 who travelled to Lake Garda by train.

Our room looked over the street but because there is very little traffic it was very quiet.
I would use this hotel again if I returned to Lake Garda.