is it easy to 'get into' online wise?
It's dead easy to get into it.
If you're a defender - you get a short time to prep the zone, depending on the operator you select; you'll have some special tools to do this - but you'll always have 2 metal shutters for vulnerable walls.
It's just about learning the maps, where to cover etc - much the same of any other online game really, you'll find an operator that you gel with - but it's a rush to select them in the lobby, so you might end up with the blank template guy - usually has barbed wire/shield as his tools.
Again, with any other MP game, you are dependent on your team mates - you'll often get people who will think an aggressive defense is best, and they'll leave the rest of the team hanging, whilst getting slotted. But at least this game is pretty decent with this - as you get lit up on the enemy HUD, if you go outside!
I played it a lot when it first came out, unlocked all but two operators, then moved onto other games - popping back on now and then, I now see there are a bunch more operators, but they cost something like 250,000 points!! That's far too much of a grind for me, so I'm happy to not bother with them; I'm certainly not going to pay for them.
It is a good game though, just remember its a R6 game - so they're trying to be close to reality, so you can get dropped in a few hits. The formula works, the whole attack and defend - but it's not hard to get yourself up to speed.