This has come a long way. I'd guess the main barriers to entry atm are that it's a sand box and some parts are more fleshed out than others, so if you just log in without knowing what you're doing it's quite sucky. Some useful links :
What is going on?? A SotA Leveling Guide | Shroud of the Avatar Forum
Use the above link to get your feet wet, kill some easy mobs, do some mining and make yourself a weapon and armour if needed.
Shroud of the Avatar Interactive Map - SotaMap.com Map
Recipes | The Order of Drunken Elders
Quick Reference Guide | Shroud of the Avatar Forum
Couple of helpful hint. It's being talked about as skill based progression without leveling, but it's good to know that you have an 'adventurer level' which affects how tough mobs are in relation to you. Press V to see your skills and its the top listed.
You have two types of XP - Producer XP and Adventurer XP. You have a pool of both. KIlling creatures and gathering resources puts XP into your pools. Using skills and crafting uses some of this pooled XP to raise skills when they are used.
It isn't really a MMO though correct but can be played as one? I remember reading up about it before I backed it forever ago but wasn't sure where they ended up with their multiplayer option to this game. If people say its decent I may read back up on it again. Last I played it was still pretty rough but that was a long time ago.
It absolutely is an MMO and most people will play it as such, but it has a couple of innovations.
1. You can play it offline in a world that won't touch the MMO. In this mode what you do, what you farm, what you make etc has no bearing on the persistent MMO world.
2. The main mode is the MMO, BUT you can choose to intermittently play in this persisten world in normal MMO Multiplayer mode or when you log in you can choose for a session to go into single player online or friends mode online. It's effectively giving you your own instances that other folk can't enter. It's a great way of keeping the persistent MMO a single world.
I used to think it was a lame idea, but I've gotten used to it and now think it's a great. You get to your favorite mining or hunting spot and if it's taken you can log in solo or with your friends and get your own area.