There was a mix-up with my weekly gaming group this past Sunday that resulted in all of our four rotating DMs thinking that it was someone else's turn to run. Most of us had first level characters for 5e built, though, so while a couple of people hurriedly built characters, I read through the first adventure of Lost Mine of Phandelver. Despite only having about 45 minutes to prepare, I ran the session, and it went surprisingly well. Here are my observations from the session:
First and foremost- The single best thing you can do for party balance is to have everyone use point buy/standard array. Seriously. One person had rolled his stats, and he had rolled really well. It was rather unbalancing. I don't think that allowing everyone to roll their stats is a very good option either. It seems like a lot of the balance inherent in the system comes from having everyone start off on a level footing, stats wise. Just a few points difference in total stats at first level made a huge difference at the table, and judging by the rules, the problem would only exacerbate at higher levels.
Second- in almost all circumstances, you should take the time to buy your equipment individually instead of taking the starting equipment. One thing I have noticed is that with the reduction in magic items in particular and the power level of the game in general, using various mundane items is far more useful and effective than it has been in the past.
Third- Passive perception wins really hard, from a DM point of view. It makes life a lot easier. However, you have to make sure that players know to be more specific with what they are searching than they perhaps used to need to be. The one tiny moment of conflict came when the party had come across a couple of dead horses in the road. A couple of players said that they were searching. I described the immediate scene with the dead horses and what they found. A couple of questions were asked. Then they were ambushed. One of the players who said they were searching said that he meant that he was searching the whole area, so he should have seen the ambush coming. I smoothed out the situation by not giving all of the ambushers surprise attacks, but i am a nice guy. They should have gotten fairly nailed.
Fourth- For me, at least, the biggest DMming difficulty was remembering to assign advantage and disadvantage. It is going to take some time for it to get ingrained in to my head. If you are DMming for the first time, put a post it note on your laptop or DM screen to remind you to always consider advantage vs disadvantage.
Here was the party, all level one:
Standard Human Fighter
Wood Elf Druid (rolled stats)
Hill Dwarf Cleric
Dragonborn Paladin
Halfling Rogue
Tiefling Sorcerer
Ignoring the Druid, who was better than everyone else because of crazy stats, the fighter was by far the star of combat, followed closely by the Rogue. The Cleric was played like a healbot, so I don't really know how first level Cleric really does. The person playing the paladin was doing such a good job of roleplaying and keeping us all in stitches that I didn't get that much of a feel for how the crunch was. The Sorcerer struggled. Granted, her spell choice was made primarily with a focus on spells that would continue to be useful in to high levels instead of spells that would be most useful at level one, but it still felt a bit weak, and definitely fragile.
Overall, I would say that the most powerful character at the table (again ignoring the druid) was the Rogue. It was the second most powerful in combat, but by far the most useful out of combat. The Rogue managed to nerf an entire encounter with a bell, some string, some more string, and ball bearings.
A lot has been said about the casters vs mundanes subject, and I will say this. At level 1, the mundanes win. I am sure that the casters will eventually catch up, and I am not sure when they will catch up yet, but don't count them out.
In the past, the thing to balance a party around has been the various abilities- healing, spellcasting, tanking, dealing with traps, that kind of thing. With the way this edition is set up though, the classic roles have become more flexible. A lot more classes can heal now. There are more classes that can be effective tanks. Practically everyone casts spells. Multiple classes can deal with traps. Hell, anyone can deal with traps if they take the right background. The most important thing to balance a party around in this edition so far seems to be skills. The attempt to de-emphasize the skills has backfired somewhat. Unless you have a bard in the party who is high enough level to have jack of all trades, it is really important to make sure that you have most of the skills covered somewhere in the party. Having the proficiency bonus makes more difference than I expected it to.