Advice on travelling by train in Turkey please - Istanbul to Kayseri?

I'm thinking of travelling on the Dogu Ekspresi (approx 8 hour journey) next month, has anyone here done this or a similar journey on train in Turkey before and is it easy enough for a lone traveller?
Any experiences and advice you can relate would be appreciated, thanks.
I should probably add I'm from the UK and never been to Turkey before.

I haven't taken that train but I've travelled by train from Istanbul-Ankara, Ankara-Adana and Ankara-Izmir. Don't expect the train to arrive punctually but otherwise I strongly recommend it. I'm single and female and have never had any problems.

In addition to the Doğu Ekspresi you could also travel by the Güney Ekspresi or Van Gölü Ekspresi whıch both leave at 17:50 arriving at 11:50 the next morning. The Doğu Ekspresi arrives 01:30 so unless you're being met by friends this could be difficult. If you choose to travel overnight there are comfortable, affordable sleepers available with air-conditioning, fridge, basin etc and an adjacent dining car.

See here for further information: http://www.seat61.com/Turkey2.htm#Eastern%20Turkey
Or here for the Turkish railways network site in English: http://www.tcdd.gov.tr/tcdding/index.htm

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An excellent way to travel in Turkey!

Guidebooks often say that Turkey has a good bus network and that 'buses are faster than trains'. But do you really want to spend 12 hours in a bus? When you can travel on a comfortable air-conditioned train, with a bed to sleep in in your own room, a restaurant for your meals and space to move around, through fantastic scenery, unspoilt by roadside development?

Train travel in Turkey can be a wonderful experience, with the best trains now modern and air-conditioned. Sensible travellers will use a train for long distances (for example, Istanbul to Kayseri, Ankara, Kars or Pamukkale) then a short bus trip where necessary to reach places off the rail network, for example Antalya or Gorëme.

The rail network was mostly built by the Germans, and the joke goes that the Turks paid them by the mile, hence the twisting and curvaceous nature of Turkish railways! However, the best air-conditioned Istanbul-Ankara trains now travel at up to 95mph and take just 5 hours after major improvements. The first section of a brand-new high-speed line from Istanbul to Ankara opened in March 2009, and journey time will be reduced to just 3 hours by 2010, beating both buses & flights. Overnight trains with sleeping-cars, some now air-conditioned, provide a comfortable, romantic and time-effective way to travel between major cities.