If mage hand being a concentration spells is the biggest change in rules you've noticed, you haven't been playing around with cantrips and spells very much. Right off the top of my head I can list that they changed firebolt from 1d10 damage to 1d6 plus setting the enemy on fire and creating a fire surface underneath them, which is even more powerful than a simple 1d10 damage, not to mention it will still burn them and create a fire surface even if you miss your attack. Ray of Frost (I believe that's the name) can knock an enemy prone and create an ice surface under them which counts as rough terrain and has a chance to knock them prone when they move over it, and yet again it can do this even if your attack roll misses. Acid Splash has been changed into an AoE attack that reduces AC by 2 which is entirely OP since reducing AC in D&D 5E is not only rather uncommon, but also extremely useful since it makes it a lot easier for attacks to hit. Pretty much any fight can be cheesed just by hitting the enemies with a good acid splash and then letting the warrior go to work.
I'm not saying to remove the surface mechanics entirely, I rather enjoy them and they really add something to the gameplay, but they are created way too easily. Cantrips shouldn't create surfaces when they hit people, only when they are actually aimed at an object or the ground at most. Also, I get that it's more realistic for fire attack to set enemies on fire, but it doesn't do that in D&D 5E for a reason and it should be left that way. Reducing the damage die doesn't really have any effect when the burn damage itself not only make up for the reduction, but actually surpasses it. Combined with the enemy having to move out of the fire surface that was created under them, which does more damage when they move through it, it makes firebolt an amazingly OP attack for a cantrip that can be spammed as much as you want.
Using the environment to your advantage is a great option and extremely useful when your party is outnumbered, but when even simple cantrips change the environment without actually requiring an environmental object such as an oil barrel or some such, it's just too much. If I shot a firebolt at a barrel of alcohol or something I could understand it exploding and making an area of fire to separate the enemies from me or some such, but being able to do basically that exact same thing just by tossing some firebolts at the ground, no matter how flammable it should actually be, is just plain stupid.
OK all good points (and yes I haven't delved into the spells much yet!). Is there a thread where people are discussing this. You are right about Firebolt (just checked it), I wonder why it was changed? Most of this stuff seems to be small amounts of mechanical change to highlight the interactive environments, but that doesn't mean it all couldn't be adjusted back to something closer to Rules As Written in the Players Handbook.
