70 was the level cap in the previous expansion, the Burning Crusade. The current level cap is 80, and that's in the Wrath of the Lich King expansion. Which means at level 70 your friend couldn't possibly have been going anywhere near the Lich King.
Actually, he still couldn't, since although the raid instance has opened, it's gated, meaning although you may have beaten all of the existing bosses, the rest of the zone is opening gradually over time.
As for loot... the average raid boss drops about 2 pieces of loot, and 2-3 emblems. Everyone in the raid receives the emblems. The 2 pieces of loot are distributed between either 10 or 25 players, depending on the raid difficulty setting. You can clear both 10 and 25 player raid settings weekly. The emblems can be traded in for loot of equal or greater value to the raid you obtained the emblems from.
In a server first guild like mine, long before the next content patch I'll find myself swimming in emblems and passing on all loot drops, which'll be disenchanted and sold, because nobody needs them anymore. Hell, we're even mostly in the same boat with our alternate characters.
I played both Diablo 2 and Warcraft 3 (both Blizzard games, yes) for years prior to World of Warcraft. Even in the first month of WoW I was playing D2 more often.
D2's online play, while free, has cheaters roaming near enough free, and no longer has content added to it. Hell, the last 'content' patch was just adding 6 new items, which were in turn used to summon 6 reused bosses with the difficulty turned up a bit. The ultimate prize was 1 useful item per class. The interesting part of D2's online play was the economy, since unlike WoW, items were traded for items - in WoW, currency is used.
Despite D2's online play being free, I'm quite happy to pay for WoW. The standard of WoW is much higher. Content is regularly developed and released. The customer service on D2 is nearly nonexistant, while on WoW you can contact the game masters with a single button click.
I don't play with children, btw. You choose who to surround yourself with. Accepting an invite to the first guild who see you will get you surrounded by children. Developing your character, applying to and joining a high end raiding guild means you'll be speaking to and playing with adults only.
For cost effectiveness... I've played WoW since EU release nearly 5 years ago. I've paid about £10 a month for it. To compare it to other games... well, I own an xbox. The online play isn't free for that, so I'll leave it out. The games already cost something to the tune of £40 each, and they last about a month or two at the very most - because when you've completed them, that's it. Downloadable content is nowhere near as extensive as a patch in WoW.
To give you an idea of how much replayability WoW has,
(+ an 80 druid on another server)
When creating a character, plan out your role for the future. Are you going to be a healer, tank, or simply a damage dealer?
I play a healer as a main, a healer as an alt, and I'm levelling another healer. I've played all healer classes at 80 :icon_razz:
Warriors, paladins, druids and deathknights (unlocked at level 55) are clases capable of tanking.
Priests, paladins, druids, and shamans are classes capable of healing.
All classes are viable damage dealers.