So how is the game? Is it close to Division 1.6-1.8?
Did they finally release a real Dark Zone? Underground/Defense in the game? More gear sets and unique builds?
It's a strange time to start playing. Honestly, it's in the best place it's ever been in terms of PVE. Lots of build variety, easy-ish to farm for builds because of the new targeted loot system, etc. It's really fun moment-to-moment gameplay going from level 1-30 and then World Tier 5.
But because the loot system is changing entirely sometime after February, the only real reason to play/farm once you get to World Tier 5 is to stash some items with really high rolls to re-calibrate later. Otherwise, your builds are going to become useless quickly, partly because talents/attribute budgeting etc. are being changed and partly because gear score is increasing.
Honestly, the PVP sucks. The 3 Dark Zone experiment has been a failure and unless the new update really shakes up the DZ experience after Feb, I can't recommend spending much time in there for fun. The dedicated PVP mode is even worse. Nowhere near the fun that Last Stand was.
That said, Year 2 content will be starting after February and the developers have stated that they have every intention of working on the DZ, working on PVP and introducing a new mode or modes that are replayable. While it's unlikely to be a straight-up copy cat of Underground or Survival, they've heavily hinted that they plan to incorporate pieces of Div 1 modes that worked in new ways.
All that to say, if it's on sale, I do think it's a steal of a deal. Great amount of content/value, the moment to moment shooting is fun, though, like Div 1, the story sucks. But if you've already dipped your toes in and are far along in the game, I'd say just wait it out until the massive overhaul comes.