Hey, i also picked the game up for 50% at the summer sale and have been quite happy! I've played bf4 and bf1 at launch with a bit of 5 too. Im playing in EU and i havent seen A SINGLE bot since ive picked up BF6, or if i have killed one its so rare i havent even noticed. I usually dont play well into the morning hours bar a few times though.
As for the gameplay in comparison to bf4 – you will notice that the pacing is faster and leaves less room for planning and adjusting, that being said the only map that is constant chaos for me is this game's operation locker "Hagental Base", the rest whilst encouraging faster gameplay have plenty of flank routes and objectives to avoid it being an outright onslaught. I somehow have a feeling you will miss the verticality of bf4 too, many maps dont even have buildings over 2 stories high, so youre left with either a street to street - room to room gameplay loop or a flat/hilly sniper's paradise type of map.
This game also lacks the flashy and risky design decisions bf4 had - you will not see levolutions or experimental weapons or floating tanks, or even the interactive gimmicks 4 had, it will just be a shooter, something you have seen before, but modernized. But since youve stuck around for bf4 until now i will automatically assume that is not what keeps you around for a game.
Another thing is vehicles in this game - id say they are much weaker, but that is not necessarily a bad thing. The tanks can be taken down easier by engies, though engi seems to have been nerfed a tad now, the helis are made of paper, but are still deadly in the right hands and the jets (even though i dont play them) seem to have the constant issue of not enough space to maneuver. That being said you will still find players who can DOMINATE in any one of these given categories and you will routinely see a vehicle player topping the scoreboard after each game, whilst still giving infantry a fighting chance against them. The fact that only 2 classes really have the means to combat vehicles well in this game helps alot too. I mainly play infantry so im ofcourse biased, but in this game all vehicles have to really be smart with positioning and awareness and i love that about both fighting and using them, the fact that vehicles are still top performers most rounds i think compliments my point.
Overall i would say try it! Its a different game for a different time, but the experience is still worth it, especially for the discounted price. The only thing i'd worry about is EA's corporate side and their management of employees/monetization.