No, from next year, the new evisa will be compulsory. You will need to get it online before you travel using the official website -
www.evisa.gov.trIt is priced in US dollars ($20 - roughly £12 at current exchange rates) so when you arrive in Turkey, you simply go to passport control and the information will show up when they scan your passport. You are advised to print out a copy of the evisa and take it with you, as some people have been asked to produce the printed copy. It's very quick and easy to do.