Just returned from Sozopol for 2 weeks from 20th July - 3rd Aug. Stayed at Hotel about 30 mins walk South from Old Town on sea front but also next to open country. Main birding was walks before breakfast every day upto 2 miles from hotel. 1st morning within 5 mins out had Bee-eaters and Red-backed Shrike in same bush then 5 mins later family party of Golden Orioles in the Cemetary !. In total around the hotel had 40 species, in order of sightings they were: House Martin, Barn Swallow, Bee-eater, Red-backed Shrike, Golden Oriole, Yellow-legged Gull, Crested Lark, House Sparrow, Starling, White Wagtail, Cormorant, Magpie, Hooded Crow, Feral Pigeon, Hobby, Pygmy Cormorant(lifer), Little Egret, Blackbird, Blue Tit, Little Owl(alas a roadkill), Goldfinch, Sandwich Tern, Levant Sparrowhawk(lifer), Mediterranean Gull, Collared Dove, Great Tit, Chaffinch, Greenfinch, Purple Heron, Cirl Bunting, Jackdaw, Olive-tree Warbler(lifer), Woodchat Shrike, Chiffchaff, Eastern Olivaceous Warbler, Common Swift, Red-rumped Swallow, Icterine Warbler, Nightingale(lifer), Jay.
I also hired a car for 2 days, 1st day near Apotoma estuary also saw Mute Swan, Great Crested Grebe, Great Spotted Woodpecker, Nuthatch and Long-tailed Tit. 2nd day drove North to Sunny Beach area and also had Black-winged Stilt.
Definite highlites for me were the Golden Orioles which were literally everywhere and giving stunning views, I saw them every day, the colony of Bee-eaters 5 mins from hotel, the Cirl Bunting singing daily on top of next door Hotel. Biggest disappointment was not finding Syrian Woodpecker or Semi-collared Flycatcher (i spent lots of time looking).
Also saw my 1st Pine Martin, also a roadkill. Bulgaria is also amazingly cheap to eat out and buy beer and I would recommend Sozopol as a holiday destination with good birding potential.