If your intrested in either of those armies. Then yes, its a very good start.
A little bit about warmachine.
Its more of a skirmish game, then per say a large scale game like
40k.
You have your main "caster" Warcaster/Warlock. (There is also other scenario's but even then, caster dies you lose)
If said Warcaster/Warlock dies, you auto lose. Its a kill condition.
Now with that, warcasters just dont fall over 15-20 ish damage boxes usually.
Now the bread and butter of the game, Warjacks and Warbeasts. They can knock models down, throw then etc.
They have a damage Grid, Heavies can take up to 30-34 damage on average before they die.
There are many combo's, tricks etc through the game, youll see more of this when/if you get into the game.
Now down to the armies, each faction has many different warcasters, and most of the time.. each warcaster makes your army play alot different.. its like owning 1 army, toss in a new caster and feels like you have a 2nd.. Using alot of the same units.
And at last, here is a link to the quick start rules if you wanna take a read through to see some of the basics.
http://privateerpress.com/warmachine/the-game