This is really a swear word. It would be better not to use it at all. Native speakers usually use it when they feel lack of words to express something very outstanding. It rather means "indescribable" in the good way))). In fact it's only the word-substitute for not enough intelligent people. You definitely must know the meaning, but don't use it in your speach ;)

I agree with Valerie Kim, it's "very good" but in very rude form. Sometimes this word or phrase with it used in ironic meaning. Also you've asked: can you please get into details? How comes that the same word means "very good" but at the same time it's a swear word. I'm a little bit confused. In Russian there are some words (rude words in general) which have different meanings from good to bad depending on intonation or context or some other things. I can't give you examples here because they can ban me :) and it will confuse me too. Historical reference: During WWII using this type rude words was important. Why? Because native speakers could easy to use it but not native spies can't. They can speak very well, but can't use rude word as a natives. So many spies was catches by mean rude words :). Sorry, my English is not pretty good, but I hope you understand me :)

this pattern can be find in other words: х*ёвина, херовина, хреновина, фиговина. etc. Also there is a word обалдеть and обалденно - from балда. You will find балда in a dictionary:))))

In Russian profanities almost all words with root 'huy' can be modified to somehting less obscene. Let huj be 8th grade of obscenity. It can be substituted with хер. Before 1918 it was just the name of X, the letter. So like 'X-word. Now people don't know what it means anymore and only use it in swearing words and one literary word (похерить, 'cancel', 'to cross a document with X-shape') which is mistaken for a profanity by some:) Because people only hear it in swerings - it became less of an euphemism and thus more rude. So охереть, охеренно - 6th grade. Better not to use with polite people:) 3d grade would be хрен and охренеть/охрененно. You can say it when parents hear you:) 1st grade is фиг and офигеть/офигенно- one of my school teachers used it - to show informal attitude and awareness of slang:) This is indeed very mild - possibly I could heard this from some professors too.

the proper spelling is 'охуенно'. Two n's. A verb охуеть which - paradoxally - could be interpreted as 'become penis-like' (the whole pattern о-[noun]-еть used this way) means "become mad/inadequate". Mostly negative (when it is not 'of happiness' or something:)). It is used to from two positive profanities: охуительный (adj.) - So wonderfully great that it can dirve you crazy. Also can mean just 'very' or 'very strong/big/...and so on' - and thus technically be applied to negative things. Still it has positive connotations. And охуенный. It is less easy to analyze -нный is normally participial ending for transitive verbs. Here this ending is used vaguely in the sense 'related to' the thing denoted by the verb above, that is to madness/inadeqateness. The meaning of the word is close to охуительный - really f..ng great. DIfference is that in the sense 'strong/impressive' its positive connotations are weaker. FInally -о form is an Adverb. Sort of '[i feel/i am/my affairs are] in a f...ng great way'