Has it matured well?  I found an AR15.com network.  Is/was that set up by users on this site, & is it still active, or has it died?

I couldn't tell you about multiplayer, but the single-player campaign alone is worth the price. 

Multiplayer is good. There have been several DLCs with new maps/game types/content, and they are all free.  It was released Oct 2016, so the gamer population isn't as high as it used to be. Still there's typically 15-20K players logged on during popular hours, and match setup times are still pretty fast, maybe 30-45 seconds, and frequently within 10-15 seconds. I don't play as nearly as often as I used to, but when I do it's still pretty fun. 

I don't know what platform you're on so I'll generalize. PS4/Xbox populations are pretty active, not as much as bf1 or CoD but enough to where there is a steady player base and matchmaking is quick. On PC matchmaking is a little slower but doesn't take more than a minute to get into a game unless you're playing a gamemode nobody ever plays (last titan standing basically). On PC the population is somewhat low but it hasn't really dropped off at all over the past 6 months, it's been very steady. Out of all the platforms xbox has the most players at any given time.

The new frontier defense mode is pretty cool and there is a solid playerbase always on for that. The ar15 network I'm unsure about, I'm on PC and I believe I joined it already but I don't know if it was arfcommers or not that made it.

This sounds good.

I enjoy "horde" style game modes, but 4-6 waves - unless ~10 min long, or so - seems a bit weak.

I forgot to mention that this is in regard to the PC platform.

Easy/regular mode is 5 waves and takes about 15 minutes total. I haven't given hard a shot yet but regular results in a few deaths on occasion if you get a nuke titan bukkake modifier for that wave.

I grabbed it.  So far, I'm liking both SP & MP-"Frontiere Defense".  Competitive MP will have to wait until I'm up to speed.

Honestly I love the game, just got sucked into pubg. I also cancelled my xbox sub until i can find a discount. As far as arfcommers, the xbox group was never super active.

There's a device you get about 2/3rds through the sp game that I enjoyed the crap out of. Like, smiling the whole time I had the chance to use it fun.

I have not played anything in a while. But i loved titanfall 2.  Some of the single player maps were just amazing & I usually hate platforming games but the levels that involved some of those mechanics were just so well done.

Multiplayer has been great as well. With constant support during the time i played. As well as plenty of free items.  Also just read they have some new elements that I have to get back on & get as well like the frontier defense or whatever it was called in the 1st game.