i've taken EAS phosphagen HP twice. i like the convenience of not having to find some juice whenever i need to drink it. it's also lower calorie than drinking it with juice. so i took the EAS stuff four years apart and about 2 months each time. i definitely noticed a quicker gain in amount i could lift while i was on it and a more solid 'pump'. some people have questioned it's long term affects on the heart since the heart is a muscle after all. that makes it sound scary. i did a ton of research before i took it and as someone who is a hyochondriac and also works in the scientific field i felt pretty safe given what i read and also the fact that creatine does occur naturally in beef (and other foods). i also don't eat beef so i figured i could use an alternative creatine source. it comes down to a personal decision of course. also, i personally have a pretty sensitive stomach (caffeine and wheat make me shit like crazy) but was not affected by creatine like some people are. i never got cramps either but i did make sure to drink a grip of water. my one word of advice is that if you're gonna take it you better stick to a regular lifting routine, otherwise you're just gonna get all pudgy. and don't take it if you are trying to lose weight because you'll see an immediate increase in weight from the water.
here are some links i found, i tried to go as neutral and scientific on my reading as possible:
http://www.sportsci.org/traintech/creatine/rbk.html (science-speak)
http://www.musculardevelopment.com/sept99/crearound.html (opinions from 'experts')
http://www.healthscriptions.com/creatine.html
(from a supplement company)
good luck.
oh, one last bit of advice is to not go ballistic on the weights. once you feel the 'pump' you may get ahead of yourself and end up with permanent damage.