Or should I  buy it when I'm the appropriate level?

I'd like to know too if it adds anything to the original campaign.

 

Wasn't planning on buying till WM2 came out, given I'm not halfway through the main campaign yet.

The full impact of the tie-in to the main campaign probably won't be known until after WM2. Thus far the connection is mostly one-way.

 

For best results, I recommend completing Act II up to the point where you return from Cliaban Rilag before going to Stalwart. There are some lore hooks that spoil a reveal if go too soon.

Does it add anything directly? No... not really.

 

But since it runs alongside the vanilla game, you can do things like travel to the White March, recruit the new companions, and then use them to play through the vanilla campaign. 

Edited December 14, 201510 yr by Heijoushin

It adds the cross-class talents for level up and increases the level cap which you can hit in the main game, but that should be about it.

 

Note that the development of the add-on resulted in several new features being patched into the maingame as well, but you already have them. So in a way, the release of white march was a major contribution to the maingame you already got.

Well, if you like the eerie atmosphere of a tundra, would like to recruit a rogue instead of creating one of your own and get your hands on the souldbound weapons as soon as possible, then go for it. Don\t go for the lich at low levels, though. Did that instance at lvl 9/10 and it wasn't a walk in the park, believe me.

I'd personally wait for prt 2 at this stage. That's presuming the end January date is on. Bear in mind though that you cannot play the expansion after you have finished the main game.... Doesn't make much sense put that way