greek are not useless but far from "powerful" like many people here are saying. i play zeus and (i think, but haven't officially tested) hades at the 1750 level.
i find i can do well against a non-rushing atln (3:30 kronos rush is really hard to face as zeus). hops work wonders vs atln. the key is to boom, take tcs, and hold your positions with hop-tox until you get the siege required to work on taking apart their base. raiding is not so hot vs them because a few katas can wreak havoc on ur hipps.
vs eggy, like armorpierce said, isis is quite difficult to beat. she can turtle without the disadvantage--map control because she gets eclipse-ancestors to help her take it back at the 7-8 min mark. don't play vs ra/set much so can't tell there.
vs norse, can handle everything vs massed rc. the rc can be in your base early and en masse before you can get enough hops. if you do get enough hops then you've lost map control. a norse player can go heroic and put hillforts around your base before you can return the favour. vs norse it's paramount that you get pressure on them before they put it on you. the game is decided very early on. again, not impossible, but you have to play 50+ pts better than your opponent to win.
vs other greeks, most of the greek civs can hold up alright to the others. the hades boom is now pretty effective. zeus can stand up a bit better to possy. i think the greek civs are pretty balanced now against each other.
the glaring weakness of greeks is their play on water. with norse you can advance before 5 min and pump longboats from 2 docks. next to impossible to do the same with greeks. eggy gets serpents that they can use to help out. alternatively, eggy can get a wood tech of all things (like they need it ). the other big hurt is a lack of strong econ bonuses before mythic.
i will say it again for what seems the 50th time: you can get good with greeks. you can even get to be 2k with them. however, you can get a rate 50+ pts *better* with civs that are stronger, such as thor, isis, oranos. the fact is some civs are stronger. greek civs are weaker. sure, you can do some good (and fun) things with greeks. but in competitive play (one guy even said he hasn't played a rated game!) other civs will see you getting a higher rating than greeks.
and that, is the point, when talking about civ strength.
ask any expert (and knowledgeable 1750+ player) if they think say zeus or thor is stronger (1 on 1) across maps and across ratings. hades vs oranos? possy vs isis?
sure greeks have the potential to be strong, but across rates and across maps and vs. other civs they are the weaker culture. and yes i play zeus, hades, thor, oranos, and am learning ra/isis so i'm not speaking from a biased position.
if you don't believe me look me up: PW_futurehermit
fh