Just got back from Sidari with my husband. Great resort for couples, singles and Karaoke-lovers! The resort is small with one main street full of restaurants & bars. Great for a week but any longer and we would have got bored.
Bars are great but restaurants provide watered-down varieties of authentic Greek dishes (all served with chips) which was a bit disappointing. We ate out every night and none of our meals were bad, they just lacked authenticity but the resort is pretty cheap; lager 2 euros, cocktails, 3 - 5 euros and meals 5 - 10 euros on average.
Bars in the centre of Sidari stay open til 7am so if you want any sleep it's important to stay a little way out. We stayed at The Christakis Apartments which were a perfect distance away (about 5 mins walk from Sidari, 10 mins from the centre) and weren't bothered by noise at night at all.
Although Sidari is all about fun, partying and booze we didn't see any trouble at all (even though we were out til 4/5am) so it's a very safe resort.
If you're after a cheap, fun-filled week in the sun with good nightlife then Sadari is great!