Hmm. I wonder what's going on.
I am getting somewhat bored of the game. The concentration mechanic is making magic extremely limited and boring. When I can only cast one fly spell and then do nothing else with concentration, that makes me limited to cantrips or launching direct damage spells (which there are not many of). There are no ways to boost magical damage. So as a wizard I get to cast fly and watch the fighter or paladin do a truck ton of damage, while I do 10 or so points a round to their 40 or 50. I can't cast any of my quality attack spells for sustained damage like flaming sphere or Bigby's Hand while I have protective or utility buffs active. That severely limits me. I have to do this almost every time against legendary creatures. That makes for a very limiting and boring experience as a caster.
As a cleric all my slots are used for healing or protective spells. I do almost nothing else but heal and buff dropping the occasional cantrip damage. I always have to be concerned about concentration spells before I cast anything else.
No one takes true strike save for perhaps Eldritch Knights or Arcane Tricksters (even they might not take it), because why risk breaking a higher level concentration spell casting true strike. The concentration mechanic has turned casters into very boring characters the higher level they get. It's far, far, far, far too limiting. They went overboard controlling casters and have turned them into boring buff machines with no other function in a group unless they want to ignore the protective measures necessary to protect the party from strafing dragons, AoE attacking mages, or the like.
I feel like once again D&D went in the wrong direction with magic. If they don't correct it quickly, this edition is going to fail to do what it was intended to do. Bottom line is D&D players want interesting arcane casters. There is no getting around it. The concentration mechanic kills that. Who cares if you have more spell slots if you can't use them because you have an active protective or utility buff preventing you from using an offensive spell. If the magic system fails, the game will fail. Until D&D accepts that lesson, they won't match Pathfinder. Pathfinder casters are way more interesting, versatile, and capable. If at least half of your player base enjoys playing casters (divine or arcane), limiting the magic system as much as they have just pushed those people into games where casters are much more interesting and less limited.
At first I didn't think the concentration mechanic was a big deal. But once you start fighting tougher creatures with major AoE attacks that can decimate the entire party, it becomes a big deal. You can't protect the party without a concentration based spell except for fire or cold damage, once you cast a concentration spell you can't launch effective offensive spells without breaking the concentration spell. Couple that with legendary resistance and magic resistance making saving throw spells almost useless pushing you into concentration magic attack spells that you can't use with an active buff, you have casters that are boring, limited, and frustrated.
I've reached the point on my wizard that I barely enjoy playing him. I feel like switching to a rogue or warrior type that doesn't have to worry about concentration. I get sick of fighting a dragon or legendary creature that automatically saves against my attack spells. I get tired of casting fly on the fighter and paladin, making it so I can't cast Bigby's Hand to do consistent damage. I'm limited to launching fire bolt over and over again with maybe a fireball that does 15 points (barely more than my fire bolt) and far less than the paladin and fighter because I have to keep the concentration buff up.
What play testers told the game designers that concentration worked? It is lame at higher level to the point of making the wizard a boring buff bot that does minimal damage and barely any effects, because they're all concentration or easy saves. Big time miss on the magic system for someone like me that likes playing casters.
Some of the other players are getting bored because writing down gold is pointless now. We have all this gold and treasure, but nothing to do with it. When the DM says "You find 3000 gold", we all shrug. We're all thinking, "So what. We buy a keep that doesn't matter. Spend our time wenching and drinking for the umpteenth time. Buy a wagon load of healing potions to preserve the cleric spell slots. Big deal."
There are problems with 5th edition. Not with balance. It's amazingly balanced if you mean martial weapon users do all the damage while casters buff and heal them. You can win plenty of fights that way. That's not the problem. The problem is the magic system is boring. I can't imagine I'm alone in this opinion. Sure, you help the party get the job done. But when did anyone play a wizard or arcane caster to be a buff bot useless in the most important battles? I know I never played a wizard for that reason in any edition. Even in the 4th edition casters felt more substantial than they do in this edition. That's strange coming from me, since I did not like 4th edition. But damn I am getting bored playing my wizard. That concentration mechanic is making my life as a caster feel like watching paint dry. Cast one concentration spell, launch cantrip endlessly. That cant' be life as a wizard or arcane caster up to high level. That isn't fun.
I hope they take a look at some of this stuff quickly. I know once I'm done playing this wizard, I doubt I'll play another caster again until this stuff is fixed. I'm going to stick with archers or hybrids. I can't take the near immunity to magic of legendary creatures, the limitations of concentration, and watching martials do a ton of damage while I use all my slots to protect them or let them get into battle. That's not fun.