I think BG 1 was better to play with your own created party (via multiplayer).

However, I'm not sure if BG2 is better that way, or if you should play single player (or a few, but not all slots filled multi-player).

I've avoided reading the spoilers, but the character creation guides hint at all sorts of things you'll miss, and I'm wondering if that's really the case.

I enjoy having characters created as *I* want them, though I realize I might not have a critical skill at later points in the game, but there are usually multiple strategies so I'm not sure if anything is really critical ... (So that might be a second question: what is really critical ? I hear the breach spell is ... )

Definitely leave one or two slots open in BG2. The NPCs have individual quests and you'll miss a lot without having room for some of them in your party.

I'm fine with using the NPCs in BGII, which I'm playing now. However, I was fine with the NPCs in BGI too.

If you do want to create your own party, I second the advice though to do no more than five, perhaps just four, of your own characters to save a few spaces for NPCs with quests.

NPC companions -- their dialogues and banters, their interactions among themselves, and their quests -- are the big, integral part of BG2. Each NPC companion in BG2 offers his/her own extended side quest, and often more than one. You will be missing out too much on the storylines and plots if you play through the game without them.

Answering the part as to what is vital- by the time you get to higher levels (Chapter 5 and beyond), I advise at least two mages in the party who can cast all those anti-magic spells (spell thrust, secret word, breach, pierce magic, warding whip, ruby ray of reversal). You'll face some powerful spellcasters who can put up multiple layers of protection fast, and having two mages dispelling in tandem is very helpful.

Other than that, party composition is pretty much the same deal as BGI. You want to try to get one of each of the four major class types. You want some healing ability, some tanking ability, melee-damage, ranged damage, and some opening locks and detecting traps.

You'll hardly miss anything by creating your own party, just a little flat entertainment.

If you want to create your own party, then you might as well just played Icewind Dale.

If this is your first time playing BG2, it's widely suggested that you only make one character, and use the in-game NPC's to fill out your party. This way you gain plenty of party banter, and you get their personal quests. I think every joinable NPC has at least 1 quest tied to them, others have even more.

Unless you really know your way around the game (which you don't if you're a 1st-time player; the game is simply too big), you'll miss out on these rich aspects the game has to offer if you create your own NPC's to go with your protagonist.

The choice is entirely up to you.

I'm just finishing up a run through BG2 (moments away from the final showdown with Irenicus), and used a custom-built group of adventurers. The NPC companions do add a lot of flavor to encounters, which I somewhat missed, but I was feeling powergamey and wanted to tailor my party to my playstyle preference. As such, I used a Kensai/Thief (dualclassed at level 13 for backstabbing goodness), a fighter/thief (to cover all the lockpicking and trap-finding before my kensai dualclassed), an Archer (because they're so much better at ranged combat than the other chumps that it's not even funny - he currently has a THAC0 of -19 and 4 attacks a round), a Ranger/Cleric (to add more fighting prowess than a pure cleric, plus access to handy druid spells), a Sorcerer (because you need a magic-user, and sorcerers are more flexible than conventional mages), and a Skald (because their supercharged bard song is AMAZING, especially early game). With that party, I had two assassins that could one-shot most problem enemies, two magic users that could mow down crowds with an arsenal of wands, and just enough support magic to smooth things over.

Again, especially if you are playing it for the first time, adding in the NPC companions will add more flavor to the game. Minsc and Jan are hilarious. That said, if you're in a mood to powergame, a lot of the NPCs leave much to be desired. Jan is an Illusionist/Thief, which is pretty handy, but is banned from using Necromancy, and a lot of the really useful kill-em-all spells like Skull Trap and Abu-Dalzim's Horrid Wilting are Necromancy. I'm a big fan of Bards, but the only Bard NPC uses the Blade kit, which trades most of their traditional bard benefits (bardsong and lore) for more fighting prowess. Yoshimo is everything I would want in a thief, if only he stuck around until the end of the game.