My experience was, making a group was a little difficult.
To use the "smart function" (F) which opens up an interactive menu, you can invite to a group etc. But this becomes difficult when someone is moving.
You can quite easily use the "contacts" menu and invte someone thats on your friends list to join a group.
Phasing happens often....and is a little annoying as you cannot interact with that player in any way. But in saying that, it may have been a little bit bugged, because if you used the "travel to player" function, it sometimes resolved itself and allowed you to see & interact with them.
There are also quests where elements are not shared with group members. For example...rescue 4 NPCs, you must all individually rescue 4, which seems a little wrong. There are quests that ask you to collect a certain amount of items, which makes sense to separate the quests to individual collections, as these are items to be put into your inventory.
Grouping for dungeons isn't such a big issue with phasing, because once you enter, you will all be grouped properly.
Although, with Dungeons, it can be difficult to use the group finder to find a set-up that works. You will often find that 4 dps are put together, and this will rarely work for bosses....and yet, there are no settings to determine the requirements you want for a group set-up. And you may also have people labeling their own abilities incorrectly......they may have a little element of healing, and claim to be a healer/dps, yet cannot heal a group at bosses. Its a complicated scenario, and I don;t know if there is a complete solution for it.
Its not terribly bad, but it definitely needs some work ....but then, the beta is likely an older build and these little bugs may have already been remedied.