Putin is using cruise missiles against dispersed, difficult to identify, low value targets in asymmetrical warfare.
For ground troops he is relying on the Syrian army with Hezbollah support, who have been soundly beaten by the rebels many times before.
He is not in a good place and this is costing him a lot.
Also it is inevitable that he will lose assets.
His strategy is to take out the rebels and leave ISIS alone. After which the world is left with a binary choice, Assad or ISIS.
Putin is very cocky, deliberately sending combat aircraft into Turkish airspace, locking radars on Turkish military aircraft and intercepting USA drones. This is a very dangerous game and the potential for mistakes is high.
Cameron is very misguided blaming the migrant "swarm" on ISIS. The refugee problem was caused by Assad barrel bombs. Now Cameron wants to send our combat aircraft into Syria. He is stark raving mad. And he hasn't learned from the huge mess he made in Libya.