Baldur's Gate 2 (& Throne of Bhaal)
Pros: Non-linear exploration of a quest-dense urban hub (Athkatla) and its surrounds, tactical mage duels, supreme replayability & crazy meta-gaming potential, a likeable villain in Irenicus (great voice, too), they added more sidequests that spanned chapters and vast areas (Human Flesh Armor, the Tanner), superior pathfinding despite equal search nodes? (congrats on that!), summon cap of five, Spellhold, made numerous incremental improvements to the engine (dozens of convenience tweaks like bulk buy, map doesn't pause game; but nothing ground-breaking), bigger budget reflected in the end-product having more polish.
Cons: Monty haul uber-itemization for small-dicked munchkins who need a compensator (some weapons have on-hit effects the enemy can't even save from and they bypass MR, like FoA's Slow & Fury's Stun), excessive, irrelevant & banal banter that nags at the player and takes the steam out of things, eight fewer companions and now they bore you with their prosaic lifestory and romance you at every turn, Prologue drags on with multiple scripted events & interjections (true of campaign in general), devalued utility roles (clerics & thieves are fifth wheels, even in dungeons), a silly overly emotional plot, can't even dual-class from or to Specialists anymore and replaced by non-core ridiculous rules bloat (e.g, PrCs, HLAs, spells out the ass), a literal adventure mart at the start of the first chapter selling all sorts of OP shit even before patches added the Robe of Vecna, Dak'kon's Zerth blade and a shield that turns a formidable foe into a kitten, a ring that sets your Charisma to 18 at the same point, Watcher's Keep was a cakewalk compared to Durlag's Tower, paperdolls are inferior, false urgency to find Imoen/Irenicus, nerfed overworld waylays & respawns (they're scripted, non-threatening and give generous rewards like hand-placed spell scrolls & Arbane), added newbie-friendly options like Rest Until Healed (rest for weeks!)/Max hit dice on lvlup/100% spell scribing that everyone pretends they're too hardcore to use, still made no concerted effort at choices & consequences (they're illusory), lengthy unskippable cutscenes of Irenicus kicking ass, clicking the rest button cures poison and disease even if it's about to kill you, forgettable after-thought locales like sahuagin city (at least it's optional), strongholds & romances are just insipid mini-games, liches without phylacteries, an unlikeable villain in Melissan, Throne of Bhaal was so bad that Gaider labored to make Ascension in his spare time with a few Wei-Du modders, and it still sucked, Sarevok can join you and be turned to good, turnip waffling, overall embarrassing uber-epicness, and finally BG2 seems to have nurtured a horde of elitist munchkin power-gamers who skipped the first game and falsely think BG2 is the best cRPG ever, better even than Fallout. It isn't, not even close.
for me, the biggest "con" in BG2 compared to BG1 was the lack of exploration. There were a series of outdoor areas/cities but they were there for a reason, and the more important quests nearly guaranteed that you'd see most of the maps.