Possibly more important than pros/cons, are differences. The two games, even though they share the same history (EQ2 takes place 500 years after EQ1), generally the same races and classes, they play as different and distinct games. I played EQ1 for almost 2 years, just past LDoN. Once EQ2 came out, I never looked back. Here's some bigger points:
Character Creation: Dozens of facial, hair, and body adjustments you can make to tailor your appearance.
Zones: No change, there are still zones you must transit to get from one place to another. There are also LDoN-style zones (Splitpaw Adventure Pack - level 20+) with scalable instances.
Housing: Now you start with a roughly 20x20 Inn room to call your own, decorate with movable furniture, paintings, sconces, tabes, chairs, chests, fireplaces, and more. Many quests award an item that can be placed in your house. There is also more expensive housing and larger in other city zones that you can rent. Our guild house is a 3-bedroom, 2-story place with a patio.
Health/Power Regen: EQ2 is lightning fast, you'll be back up to full power in just a few minutes, faster if you have good food/drink on, even faster if you have a healer and Breeze-caster. Sitting has no effect on regen. All this results in less downtime and more killing.
Content: About 1/3 of the content is solo, enabling anyone to log in and kill. However, solo mobs drop not-as-good loot. Heroic and group mobs drop better loot. Like another mentioned, the progression of zones are very narrow with little expansions for lower levels. But for a new player, the world is huge.
Combat: EQ1 only gave you 8 (or is it 9?) action buttons, so selecting the right combat spells to use was tough. EQ2 has virtually unlimited 12-button hotbars (action buttons). You are only limited by how much real estate you have on your creen. I typically have 5 12-button hotbars up with all my spells, buffs, and abilitites.
EQ2 has Heroic Opportunities, which is when a special sequence of attacks are made in a particular order from party members, a special event happens. It could be a temporary buff, heal, or extra damage. Anyone can start it, a HO wheel appears with flashing icons that correspond to a class spell/skill. Match the icon within 10 seconds and it works.
Combat can be locked or unlocked, selectable by the leader. Locked encounters do not allow anyone outside the group to affect it. So no heals, buffs, or kill-stealing. Unlocked encounters allow people outside to cast into the mix. The party must do at least 51% of the damage to get credit and loot.
Movement Speed: During combat your speed is slowed drastically, so it's harder to run away. You can buy horse, speed buff totems, or quest for a flying carpet to increase your movement speed. Some classes also have the traditional Spirit of the Wolf spell to increase their speed. Travel within many zones is done by riding a griffon between towers in the zone. In higher zones, you ride a magic carpet, and in even high zones, you ride a cloud.
Levitation: Not here, unfortunately. I miss it.
TRAIN TO ZONE: No such thing in EQ2. Now, mobs will only chase you for maybe 1/6 distance of the zone, then de-agro and return to their original spots. During their run-back, they are non-agro to anything.
Mob Socials: Almost all mobs are not social, so you can safely pull a single from a group of singles. Others are grouped (linked) and when you select one, all the other linked mobs will also highlight. These group mobs are harder, and when you attack one, the others will run after you.
/CON: There is more granularity to how hard a mob is. It is indicated by up or down arrows. So a vvv (3 down arrows) would be very easy to kill and worth almost no exp. A ^^^ (3 up arrows) is extremely hard, results in almost certain death, but is worth very good exp. Mobs will have 0-3 arrows. Zero arrows is actually the "middle-ground". It is further emphised with "Heroic" = very hard, and "Epic X2" = extremely hard, don't even attempt with 2 groups.
Graphics: Light years above EQ1. Better combat animations with sword sweeps, magic spell graphics and effects, sounds, and more. When you go into battle, your facial expression changes to a angry battle-snarl of death, and you withdraw your weapon into a battle stance. When you kill something, it will stagger, legs buckle, and slump to the ground. When standing, your head (but not your view) will turn to look at whatever is passing by.
The graphic settings, even at the lowest, are more detailed than EQ1. You can set them all the way up to a crazy level that would melt your computer. Seriously, there is no computer that can play the game on the highest settings. Well, maybe NASA can...
There's more, but the list could keep going. I recommend you try that free playable demo version of EQ2 (Trial of the Isle) to see for yourself how it plays and how it looks. It has a very good tutorial. I promise you won't be dissapointed. :)