There are some good points made in previous reviews. Planes going into the airport fly straight across the middle of the city so you can't avoid them - and without them you wouldn't get here! Fortunately there aren't too many. There is a mosque loudspeaker pointing down into the open centre (swimming pool / restaurant) of the hotel, but fortunately the aural assault is short and sharp - it will almost certainly wake you up at 5am but you should be able to go straight back to sleep. But during Ramadan (Aug 2011) when full decibel "prayers" go on for hour after hour staying here must be intolerable. The newer rooms are across the back of the hotel. Its a traditional Indonesian hotel - in my room there was an AC but no telephone, kettle or fridge/mini bar and the TV had terrestrial channels only. The room was in reasonable condition and the bathroom was ok. The staff, and there are plenty of them, seemed typical for Indonesia, a few were friendly, the rest did their job. But breakfast was particularly poor - as mentioned elsewhere you will be asked to choose it the night before. No problem with that, but it comprised one tasteless egg (no seasoning - there was no salt or pepper on the restaurant tables either), 3 slices of toast, poor quality jam and a glass of reconstituted orange juice. No fruit, in this country where fruit is so abundant! If you need to work make sure your room has a table and chair - the older room by the pool which I saw did not. The hotel has wifi but I didn't try it.
So what are the good things about this hotel? Location - just 2 minutes walk and you're in the middle of Jl Malioboro. Also you can walk up to Jl Sosrowijayan in 5 minutes if you want to find some western style food, travel agents and more hotels and guest houses. The pool / restaurant area at Peti Mas is delightful, particularly at breakfast time when the birds are singing, a tranquil haven most of the day, as long as there aren't too many other guests around, which there weren't. The staff put a lot of work into manicuring the garden and the plants. You can get free tea and coffee at the restaurant pretty much on demand. They have a big fridge (courtesy of an intl soft drink company) but I couldn't see any beer in it and not on the menu either. My guess is if you needed to keep something cold for a while, such as a bottle of beer, they would let you keep it in there. At the price (Rp 447,000 = $50) for a double room Peti Mas is not particularly good value - you're paying a lot for the location. If you're not bothered about being in the city centre and just want to relax in Yogya then there is better value elsewhere. On a general note avoid Yogyakarta altogether when there are public holidays - you'll struggle to find a room as Indonesian tourists flock here for the shopping.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.