I’ve found Counterspell to be a pretty positive addition to my encounters. It encourages players to watch when enemies use their reactions, or try to bait a reaction. Rather than frustrating, the players have turned it into part of the game.
I’m also kinda meh about the whole arcana check thing. Casters generally have high DPS/versatility. I feel no need for them to be able to horde their spell slots further. When the party is facing an enemy caster, they announce that they’re casting and I tell them if the enemy caster counterspells.