This is a very nice walk with lots of variance in the scenery. It is well posted and relative easy (no climbing) but really steep at times and not for those who suffer from vertigo....
The path starts in Agios Ionanis but we cheated a little and parked the car on a dust road a little before the town (see map). From here it is 9 km. to Agia Roumeli. First a walk on the plain along the dust road (in our case) and on the well kept paths (see pictures) to the steep slopes of Seloudha (See pictures).
Then. down hill until you reach E4. The first part is like walking down the Aradena gorge from the bridge on the old Kalderimias - it is in good conditions. Then steep downhill in shades of the pine forest until E4 on a well kept track.
Down on E4 you soon reach Agios Pavlos and the welcoming taverna (open in October) and then another 1 1/2 hour partly on a path along the cost and patly on the gravel beach. This part is exposed to sun - so bring water!
As said a lot of variance in the scenery and really worth while..