Gule: The way I see it, whether you should get IWD2 depends also on what you enjoy about these games. Is it the story, the tactics, coming up with original characters or trying to beat the game?
Personally, I greatly prefer Icewind Dale over it's successor.
That's not to say that IWD2 is awful or that I didn't enjoy it at all. However, the part that I enjoyed the most about the first game was that it oozed atmosphere and style.
As far as I'm concerned, IWD2 is seriously lacking in that regard, though I find it hard to pinpoint to the exact reason.
Bottom line:
If you play these games for their tactical depth, because you like to employ different strategies for overcoming difficult battles and because you like to come up with efficient character builds, get Icewind Dale 2!
However, if you enjoyed Icewind Dale mainly for it's atmosphere and story, I can't really recommend it's successor.
Hope this helps! :)
Sounds very much like my experience too - except I disliked IWD2 so much that I never finished it (probably not even close). Dislike is perhaps harsh, but I found IWD1 to be much better. The atmosphere and music is simply stunningly beautiful. Some of the locations are glorious to behold. The story was decent enough as a placeholder and kept things moving forward. There are tough battles, but not exceedingly rough.
In IWD2, however, there was just horde after horde of enemies, not much of a story, and the atmosphere simply wasn't as good as in the first game. Ofc I didn't play the whole second game, but it sounds like it didn't rectify these problems in the later stages.
Must also say that I disliked the new ruleset. The BG-BG2-IWD set worked really well I felt, and this new stuff was a bit weird, and not in a good way. Bit of the same in NWN2 really, which I also didn't finish.
One of the combat mechanics, if one can call it that, which I really didn't care for at all, were these damn monsters that kept spawning in our midst all the time, due to some guy on a drum (doesn't sound silly at all, right? :D). I can't stand phase spiders in the BG world for the same 'mechanic', but these beasts were absolutely everywhere.