Pros
+ Versatile champion
+ Great initiator
+ Grab + Fist combo is great near turrets
+ Nice passive
+ Very good in teamplay
+ So Fun! :)

Cons
- Needs good team communication
- Not too good farmer during early game
- Not a killer....u do a lot of assist!
- Hard/Long to build

Rocket Grab
Definitely Blitzcrank's main ability. This is what makes your enemy afraid of you and your team love you, given that you can use it well. I could write a whole guide about this ability, but I want you to learn the finesse of it by yourself. So I just say few things:
- It can be used effectively to grab enemies through walls. Having someone to scout the other side of wall makes this easier, if there are no minions. Also this is the reason why you should consider picking Clairvoyance.
- Using Power Fist right after a grab makes you a nice combo
- During early game, use it to pull enemies to your turret. In experienced player games it wont be easy, since opponents know the trick and hide behind minions.

Overdrive
I'm mostly boosting movement speed with this since this build doesn't raise attack damage at all. During late game this will be active almost all the time and you will probably be the fastest character in your team. I put one point on it before level 6, but after that I don't raise it until I have to.

Power Fist
An ability that works well with your grab. Raising the level only decreases cooldown, but that really doesn't matter. Good crowd control and with low cooldown, it will be hard for your opponents to run away.

Static Field
Good ability to finish your damage burst after Grab + Fist combo. If you are pursuiting an enemy and there is no minions around, you might want to let passive effect hit a few times before activating to ensure you get a kill. Also good way to farm minions during late game. Just activate it in the middle of the group and they all perish. With low cooldown it doesn't feel like wasting the ulti.

Mana Barrier
Some champions have bad passive abilities but Blitzcrank's is awesome. It gives you the lacking survivability so you don't need to buy defensive items. Gets boosted by mana items, which makes it even better on this build.

Ghost: With the second skill u run lika an airplane...u are ingancable with the shild and with this spell too.

Cleanse: For Stun slow and other spell that can kill u! In combo with the second u can follow an enemie too if he use exauste! ;)

Other

Flash
Clarity

With a good team u grab an enemie with Q, then, u use the E for knocking him and for doing a lot of damage for the Sheen, then with the ultimate do not allow to enemie to escape and if he run u can follow him with W!

Thanks to manamune u can spamm the second and the E, for increase your damage!

U cannot rest without mana!