Some commentary.
- Wizard slayer, and the spell failure chance: "It is a bit more useful if you're fighting enemies like clerics." No, it isn't. It is completely ineffective against divine spellcasting. The spell failure chance applies only to arcane spells. So the kit is somehow even worse than you thought.
- Kensai. 100% agree on the "hard to play" aspect. They're simply not tanks, and that's counterintuitive for a fighter kit. They have to rely on skirmisher tactics, hitting hard and then moving away from the retaliation. Which is one reason why the thief dual works so well - becoming a dedicated backstabber makes it obvious how to play. (Also, the high-grade synergy: damage from weapon mastery and the kensai passives is multiplied in a backstab. A kensai->thief dual is the best backstabber in the game, bar none.)
- Barbarian. Weird trivia: mechanically speaking, they've always been fighters in every one of these games that have them. Labeling them as a separate class (like they are in PnP) was always just UI trickery.
- Archer. Melee weapons are useless? No. Even if you never attack with them, every character that primarily uses a ranged weapon should have a ranged weapon available on switch, at a moment's notice. Because ranged weapons take a massive to-hit penalty against targets in melee range, and melee attacks against someone wielding a ranged weapon get big boosts to hit and damage. If you're an archer and someone closes with you, you switch to your melee weapon and then run away.
- Comparing shapeshifters to kensai? Completely different tactically - basically the opposite. You're either a backline spellcaster or a frontline tank; greater werewolf form is an absolutely amazing tank (as of the latest patch: Base AC -6 plus 20 DEX, 50% resistance to all elements, 40% magic resistance, regenerate 1 HP per round). You're just not both at once, and you can only switch between them a limited number of times per day. Also, your tank mode is pretty weak on offense - the only to-hit bonus you get is the form's strength, and the druid's wonky level curve means you spend a long time with subpar base THAC0.
(Oh, and Barkskin heavily mitigates the primary drawback when you're in caster mode; it sets your AC to something matching mediocre armor, and once you have a few levels it lasts the whole fight. Not like you had much else you needed those level 1 spell slots for.)
- Abjurer, diviner. Don't ignore the other half of the specialist equation: what spells benefit from the saving throw effects? In the case of the abjuration and divination schools, absolutely nothing. That's a serious hit against them as specialties.
- Conjurer. I'd rate Detect Invisibility as another high-value divination spell. The key thing about it is that it casts very fast; it's the absolute best way to reveal that thief you know is around before they can backstab you. Divine casters get the same effect, but at a higher spell level (3 instead of 2) and a much longer casting time (9 instead of 2). Which makes that spell (Purge Invisibility) terrible.
- Enchanter. Hard disagree. It's lackluster in BG2 (because there are no high-level enchantment spells), but it's amazing in low-level play such as the BG1 campaign. Making saves against your sleep and charm and confusion spells two points harder is fantastic, and you can still use wands when you want to blast something. For BG1, I'd rate enchantment and evocation as the two best specialties ... and both of those have a recruitable NPC.
- Swashbucklers. Really, they have a "hard to use" problem. Because you think of them as "budget fighters", but they can't fill the standard fighter role of a tank. They don't have the hit points, and they don't have the AC until high levels. But you want to use melee weapons, only you don't have backstab to really hit hard, and you think you don't need stealth but you really do if you want to close with enemies without being targeted and attacked down. 90% of the time, you're just better off playing a fighter/thief multiclass.
- "Pickpocketing's so useless in these games". Well, the thing, is, it has one major use. And that use is absolutely busted. Shoplifting. Plus if you buff your skill high enough (stack potions), there's literally no chance of failure when shoplifting. Get absurd amounts of free stuff, get actually unlimited gold if there's a fence around that can be stolen from (there are in BG2), completely break the game's economy.
- Monks. Ah, I see you don't know how to play monks. Again, they're not tanks. They're skirmishers. Move in and out of melee to hit hard when you can and dodge retaliation. You've got bonus movement speed. You've got stealth. You've got long reach with your fists, and quicker attacks with manufactured weapons. All the tools for tricky play - use them.
Now, is the monk good? At low levels, still no. But played well, they're OK, and they scale to become genuinely good at high levels. I've run with Rasaad in my party in BG1, when monks are at the weakest ... and he still basically did his share. A bit less than a sixth of the kills. In BG2 ... well, he ended up #1 in kill XP when I did my no-spellcasting challenge run. Ahead of Korgan who dual-wielded Crom Faeyr and the Axe of the Unyielding. Ahead of my fighter/thief protagonist, who dual-wielded and eventually reached the full 5 APR. Ahead of Keldorn, and Mazzy.
Oh, and immunity to nonmagical weapons is actually very good even in ToB. You know what enemies have non-magical weapons? Mists. All of them. Even the scary ones like vampiric wraiths.
- Shamans. No, the main thing about the class isn't the dance. The main thing is the spellcasting - you get sorcerer-like casting of divine spells. You're a full spellcaster, with a lot of flexibility. And when you're out of spells, or don't have anything relevant for this particular fight, then you start dancing. (Also, spirits do completely trump certain threats. They're immune to psionics and level drain, so they just auto-win in any fight against illithids.)
Though the overall effect of the class is just ... balanced. All sorts of abilities that look cool, but there's something holding them back so you never actually break anything. Spontaneous spells from the druid list? Yes, but you've got the mage/sorcerer XP table so you're just that key bit slow to reach the powerful level 5 and 6 spells unlike actual druids who get them really early with their wonky table. Unlimited free summons? You can't control them and they take time to show up, so you have to pick and choose the fights you use them for. Weapons like axes and bows? You still don't get specialization or extra attacks per round or even cleric combat buffs, so it hardly matters what weapons you use.
- Cleric/thief backstabs. Actually, you can backstab with staves. And they're some of the best backstabbing weapons out there. A backstabber with the Staff of the Ram ... that thing one-hits fire giants.
Overall rankings ... serious tier inflation here. Planning in advance to actually spread things out more evenly across tiers would make the rankings feel a lot better.
