It's a very situational item.

/if/ you are a melee hero without much chasing power but wants early game kills in situations where supports might not be available to help.
/if/ you are against heroes who are going to farm and you absolutely need to prevent them from farming, /unless/ you are going to be attacking more than once every 2 seconds, in which case just put the money towards wraith.

If you just want to spend gold and wards are on cd, buy tps/sentries/dust/smoke/tangos, these will almost always be useful in every game.

earth spirit is fun once you learn him Anyways, nothing to do against a huskar once he gets an armlet.

You need stuns!

Yeah I know, but earth spirit is full magical damage, and its stun isn't Long enough

ES not really a dps though...

when es gets a 5 man silence off, dem feels...
last so long, it might as well be permenant.

also dem feels when you think you survived that horrible teamfight and this giant rolling ball of death suddenly lands on your head...

a really frustrating hero in the hands of someone who knows how to play him.
/care about him if the person isnt amazing though.

I love to get the early kills, roll on to someone and kick them in to your tower or back to your team mates. If you get an invis rune it's great.

I started to keep a bottle on him, then normal boots and rushing force staff. After that I don't see any mana lacks (its int/level earn is really big). Is there any problem with it? I'm considering getting treads instead of arcane. Buying the intelligence staff instead the mana booster and evade doing arcane (with that intelligence, the movility will be easier with the rolling ball).

Are you running him mid? If so I think bottle and treads is a good choice, great synergy with those two items obviously and considering his mana pool switching will be pretty useful.

Depends on the rest of your team though, if they are going to have mana problems then boots will help out a lot. Rushing pipe or mek might be a good idea.

bottle is all the rage on alot of heroes lately, seems to be the current meta for bushing and offlane aswell. a doom with a bottle just never has mana or health issues.
and with mids bottle crowing so often now, it leaves the runes alot more open for the rest of the players on the map, the whole point is to just deny the rune to the enemy mid, so you can be guarenteed to get the rune atleast once in the early game to buff up your bottle. 6 charges without having to go back to base is pretty cost effective.

pipes great, or even just the hood early, but i dont think mek is necessary, let the #4 get it or something.
force staff is great, although it can be argued that the whole point of the ball is the same as the force staff, but imo, you can never have enough mobility.

realistically, ES is never going to be much of a damage dealer, so utility items are generally best, pipe, force staff, drums, shivas etc.
just run around screwing everyones teamfight.

it seems im the king of assisting lately, been getting some crazy high assists the last few days
http://dotabuff.com/matches/456012464
http://dotabuff.com/matches/459396916
http://dotabuff.com/matches/455027389