We were booked into this supposed 4* hotel by Turkish Airlines for 2 nights when they cancelled our flight.
It is well located just off Taksim Square so bus and metro services are on the doorstep.
Staff were reasonably friendly and helpful, rooms appeared to be clean but the hotel has all the charm of a left luggage depot. When you walk in the door you just can't help feeling sad...and that is not the emotion I expect when first checking in...the lobby is depressing and the lack of lighting does nothing to help (half the area had no lights on at all). On the first floor the restaurant area is large and lack-lustre with lighting more appropriate to a bus station and certainly not somewhere anyone would want to sit for a meal. (which we had to the first day we arrived for lunch but after that we just ate out as we did not want to sit, on our own, in the empty dining room, particularly as there are so many great restaurants in the area).
The standard rooms are long and narrow and felt quite claustrophobic - however the reception did offer us an alternative room on the 8th floor which was a lot better in term of light and there was a balcony outside which offered views over the town to the Bosphorus. (However we could not get out to it as it was locked). The bed unfortunately felt like it was made of straw and while the sheet fit the bed the duvet only came to the top edge of the mattress so luckily the heating worked as otherwise it would have been rather cold as the moment someone turned over in the bed..the duvet would stop covering you.
The "amenities" offered in the room were a small bar of soap by the hand basin in the bathroom (and only when in the shower did it become apparent that it was the only piece of soap in the room !). The bathroom itself was small with no external ventilation. There was a tiny sewing kit in the desk drawer. The "mini-bar" had seen better days and needed a clean (both inside and around the cabinet) The room was carpeted but also felt a bit like straw underfoot.
The lifts were rather small and dark and well worn..and the hallway carpets just looked like they needed replacing. There is a pool, sauna and hamman area in the basement..but it also seemed small, dark and well worn to the extent it almost seemed seedy...(plus there is a 10TL additional charge to use the sauna). The whole place has good bones...but the appearance of being managed by people with no interest in customer service. If you want a bed in a hotel near to Taksim Square this passes the test but don't expect anything other than the bare minimum.

Around Crystal Hotel you'll find a lot of other Internationl Hotels on Istanbul's "Hotel Island" just 50 m from the Havas Bus Istanbul Taskim Square. Around the hotel are a lot of nice and international Restaurants (japonese, frenh, turkish, thai, italian...) and the main shopping street is close. Good breakfast, normal rooms. 'Would come back.

I went to Istanbul on a work conference & was advised we were staying at the Crystal Hotel. All the reviews were not great so I was not expecting much. This hotel is a 5 min walk from Taksim Square. When I arrived at my room, I was pleasantly surprised. The rooms were a decent size & the beds & pillows were very comfortable. The bathroom was also great, except the shower was in the bath (with a glass door which I loved) but some people could find this difficult getting in & out as the side of the bath is higher than normal.

The breakfast is not great but I found Istanbul pretty affordable so was happy to go have breakfast else where...so I do recommend taking the room without breakfast.

I highly recommend this hotel if you are a true traveller, meaning you just need somewhere which is clean & safe & to sleep...as the rest of the time you will be out & about.

this was our first trip to Istanbul.the hotel was good sp. good situation in taxim square.the worst thing about all the taxim hotels is the crowd and noise.from 7 am to12 pm you coud not open the window.the staff were good but the management was poor.one ofthe front desk man was unpolite and somehow rude.