Pros / Cons

Pros
Very strong ganks
Can build tank or damage
Fairly tanky
Strong base damage
Hard to catch
Has 4 legs
Good burst damage
Cons
May be picked on
Not the best tank
Medium Skill cap (E-Q combo)

Abilities

This section serves to give a little rundown on Hec's abilities, in case you are not too familiar with him.
Warpath
- Hecarim's passive. This gives Hecarim damage based on his bonus movespeed. It also gives him the ability to run through minions without experiencing unit collision, which can prove very handy. My only note on this is that you shouldn't fall into the trap of building all movespeed for the extra damage...it isn't worth it
Rampage
- Hecarim's Q. Hec's Q is a small AoE AD based ability that he generally maxes first, because it is his main source of sustained damage when clearing and ganking. This can be used immediately after an auto attack to maximize its damage.
Spirit of Dread
- Hecarim's W. This is one ability that I think is very underrated. It heals you based on damage any team associated unit deals within the circle. This means that if you are being tower dove, and you have your W activated, the damage that the tower, yourself, and all allies are dealing is factored into the healing. Fighting people in a group of minions with W on is a great way to surprise an opponent with sustain.
Devastating Charge
- Hecarim's E. This ability, though maxed last, shouldn't be overlooked. It gives you a great burst of movespeed (increasing your AD) and does damage to the first unit you run into based on how far you traveled with the ability activated. This does work on towers and champions alike, so to maximize your damage, use this a few seconds before you expect to make contact with your target.
Onslaught of Shadows
- Hecarim's R. This is the reason Hecarim is such a nightmare. It is basically a Malphite ult, except it also pushes people in a direction away from Hecarim. Using this, you can ult slightly past someone, forcing them to run back towards your team.