I bought Thresh today, and because top is my main lane, i played him there.

What's my first impression of Thresh?

He clearly doesn't have the best early game, because he doesn't deal that much damage and is really farming dependant. On the other side, you got a way stronger mid- and lategame, if you collect your souls properly.

Of course i will tell you the Pros and Cons of Thresh on top.

The most important thing about Thresh on top is the farming. Because your armor and ability power are stacking with your souls, you need to collect mostly all of them. This gives you an advantage in the early game: with your extreme high basic-attack range, your Death Sentence's passive and your Dark Passage you can farm the lanes and collect the souls, without getting in touch with your opponent.
Your range allows you to stay far behind your minions, from where you can lasthit with the bonus damage Death Sentence gives you over time and maybe to harass your opponent toplaner, who maybe is melee.
You are very attackable, when you collect the souls. Why? The range, in which Thresh collects the souls is very small, and you need to go into every creepwave to collect the souls, from where the enemy champion can easily harass you. With your [Dark Passage]] you have a way to collect your souls, without being attacked: if you place your lantern from Dark Passage into the creepwave, it will collect the souls for you.
This gives you an advantage, when you are low for example, or when you wards ran out, because you don't even need to kill the creeps to get your souls (what makes Thresh so good for supporting).

I'm still working on the guide, i just published it, to show it my mates.

I would be glad, if you gave me some hints, what i could do better about the guide, because it's actually my first one.

Love,
Leggodt