First of all some Screen shoots:

This was my first time having a character over 90 level, yep my first Wizard lv.90+ (The screen is small 'cause i play like that in order not to be surprised by any monster around xP).

My Second level 99 High Wizard, in Spanish RO, sitting in a city with my cute pet Umbro *-*.

Gio training in the old Juperos Dungeon lv.3

With my wife back then (Years ago), after killing a Dark Lord (Mvp/Boss Monster).
As those screens are pretty old, i'll be sure to post some new ones, i'll take them later xP. Btw, all of those that are playing or have played RO, feel free to post and comment your own screen shoots ^^.
Ragnarok's specialty is the classes in the game, RO is basically the MMO with the biggest variation of classes; Novice, Swordsman, Knight, Crussader, Lord Knight, Paladin, Magician, Wizard, Sage, High Wizard, Professor, Acolyte, Priest, Monk, High Priest, Champion, Archer, Hunter, Bard, Dancer, Sniper, Clown, Gyspy, Thief, Assassin, Rogue, Assassin Cross, Stalker, Merchant, Blacksmith, Alchemist, Mastersmith, Super Novice, Star Gladiator, Gunslinger, Taekwon (boy/girl), Taekwon Master, Ninja, Soul Linker, Death Knight, Dark Collector, and the classes are most likely going to increase in the upcoming updates. (RO episode 13 i suppose).
Ragnarok is an MMORPG that differs from any other MMO, 'cause of:
1.-In RO you actually have full control of your own character, which means, the fact that you are a certain class, doesn't control at full your stats or builds. In RO every time you level up, a certain amount of Stats Points are given, and you chose what stats increase according with the build you have in mind. This implies, that even if someone is a magician, if he/she doesn't know how to play, then the character may end having a low power in MATK 'cause of not giving enough INT stats points to the character. (Of course every class has a certain bonus, for example, a High Wizard job level 70, have a +17Int bonus). In addition, every time you get a job level, you gain a Skill point that is used to level up a skill (Each skill has a certain level limit), plus there are skills that needs some others skills at a certain level to be learned (For example, to learn Jupitel Thunder you need, Lighting Bolt lv.1 and Napalm Beat lv.1) that forms your unique Skill tree, that differs from the others skills trees even if the others players have the same class and level.
2.-In RO, there is an unique, and really interesting system when talking about equipment. Basically, in the game every monster drops a card. For example, Pupa drops 'Pupa card' at 0.01% chance. Every card has its own info and effects, taking the Pupa card as an example, Pupa card can be compound on an Armor, and nowhere else (no Headgear, no Foot gear, no shield...). And the effect of the card is, MHP + 700. This implies that if for example i have a Silk Robe, y the Silk Robe is Silk Robe [0] (No Slots), is basically useless 'cause it has the same effect as a Silk Robe [1] (1 Slot), but Silk Robe[1] can be compounded with a card (There are tons of different effects in the card, such as anti-frozen, % chance of auto-casting a skill etc...). What is more, some card when compounded together can act as a combo and give except from their own effects a combo effect. There are also equipment that can combo with cards or equipment. Therefore, you must think well your character, your skills, your stats, and your equipment, as well as the how to use them in different situations to play well.
3.-Ragnarok has actually a Story, although as a MMORPG its story can't compete with a good Rpg(offline), it still has a good story in it. Basically the reason it can't compete with a Rpg's Story is 'cause of the Story development, as in fact, Gravity has made a good job making up stories, for each city, for the War of Emperium, for each monster, and for most of the items, as well as dungeons. However as a MMORPG those can't actually develop as well as in an off line Rpg. However, according to Gravity the upcoming episode (RO Episode 13), is going to change the world of MMORPGS with a great impact. According to interviews RO will insert a story development that can rival those of the off line Rpgs, and everything will begin with "The Destruction of Time" (This is going to be a worldwide event, regarding the city of morroc and a legendary Mvp(Boss) Monster of the past, depending on the result of the event (Who, how, and how mane time did it take to beat the event, or if the even couldn't be beaten) RO the game itself will develop according to that result. What is more, 2 new countries are going to be presented by Gravity, and as they promised, new classes, new Siege Mode (like War of Emperium, with different functions, rules, and systems). Also Gravity announced that RO will use a completely new system not used before by any game, that will allow the flow of a Story development inside an online game.
4.-There are more, but i got tired sorry xD. i'll just leave links below for those who want some more info about the game.
http://www.Iro.Ragnarokonline.com : This is is the official website for English RO, have some useful information especially for beginners, but is not fully updated, as it works with the Iro database, (Kro Database is the most updated one).
http://www.ratemyserver.com : Has a huge database reagarding items, Quests, Skills, Characters, etc.., almost fully updated ('cause Ragnarok Online is updated a lot, is almost impossible for any site to be fully updated, not to think that the old database itself is HUGE).
http://rode.doddlercon.com/db/ : A database Engine, having some useful tools, and info similar to ratemyserver, also have guides to the last 3 episodes of Ragnarok (10.3, 10.4, 11.1)
http://ro.doddlercon.com/wiki/index.php?title=Main_Page : The best website for News, and such...