Their starting infantry and position is always a deterrent for me.
Their starting infantry is a problem, but with several fast-growing cities (Sinope, Nicomedia, Sardis, and Pergamum) you can be at pikemen pretty quick. Their starting position is arguably one of the better ones. Access to Greece fairly quickly, and the same for the Middle East. Nearly every city to capture is a port city, and you have access to all seven Wonders by mid-game.

The merc pool is excellent...Cretans, Arab Cavalry, Sarmatians (until you get Cappadocians), Ellies, and Bastarnae.

What's not to like