Depending on your level your restricted to certain game types....
Roughly 6mths ago they introduced 'Sandstorm' addon which was a large outside area with quests you can use to help level up, although GA is not an MMo in the true sense. The queue system can be accessed anywhere at anytime, be it waiting in line for the 4man instances or matches. The small instances are a good way to collect loot and crafting materials, again unlike most MMo's you can only craft certain item's.
The game gets better the more you level up, and don't forget you can always respec your skills meaning you can always switch between say healing spec or poison spec.