What sounds in your language do foreigners find hard to pronounce?

For Modern Greek, the following sounds are cross-linguistically rare, and certainly rare among European languages:

• ɣ ~ ʝ: γάμος, γέρος
• x ~ ç: χάμω, χελιδόνι
• ɟ [the palatalised allophone of ɡ]: αγγίζω
• ð, θ: δέντρο, θάμνος
• r: ρέμα (people really don’t deal well with trills)
• Initial clusters like ks, ps, vl, vr, ðr, ðj, ɣl, ɣr: ξέρω, ψέμα, βλέπω, βρίσκω, δράμα, διάνα, γλόμπος, γράμμα