While BG2 is a good game, it has several glaring flaws which detract greatly from the game.
One is that it makes significant assumptions about your character, in it's moral compass, emotions and desires. BG2 assumes you care about Imoen and assumes you've traveled with certain NPCs from BG1.
The entire set-up centres on having to rescue Imoen, and pairs you with NPCs whom you are expected to have had a history with. Both can severely impede the enjoyment of the game right off the mark if either or both assumptions are significantly wrong.
Then, having shackled you to the "save Imoen" plot, you're dumped into a completely irrelevant and lengthy series of adventures that have nothing at all to do with saving Imoen, aside from the metagame of becoming more powerful to rescue her. Sure, you need to gather gold to pay for the promised help, but with the colossally bloated loot system (see upcoming point) it takes no time at all to get that money. But by then you're caught up in the sprawling Chapter 2 quests and it would then seem incongruous to just dump those, and even then if you did, you're probably not strong enough to tackle Spellhold.
The loot. It's obscene. I've always maintained that the loot distribution system seemed designed by hyperactive 13 year old boys, wanting to cram in every possible super weapon they could. It doesn't take long before you're selling as junk greater artifacts than the Hall Of Wonders museum houses.
Aside from these flaws, it's a solid game. It's gorgeous to look at, the NPCs are well developed and interesting, and it's entertaining to see the range and depth of inter-party dialogue between the various combinations. Quests are good and all in all keep you in the game.
Combat is debatable. To some it's wonderful, to others it's tedious. There's a ton of rock-paper-scissors magic-centred fights which I personally hate, requiring the player to really have a handle on the D&D magic system (something I've never really had).
Party control is again subjective. Some folks love controlling a full party, to others it's a chore. At the time BG2 came out I liked the system a lot, but now, I tend to prefer one character since it's more RPG-like - I find controlling a whole group to be more gamey and less role-play.
So, why didn't you like BG2? Could be any of those things.