Pre 3.05: 7-8
With Patch 3.05 and the White March: 9 (more of an 8.7, but meh).
I like the world and the companions, at least those I consider the core (Edér, Aloth, Pallegina, Sagani, Durance and maybe Grieving Mother). The world is more down to earth and calmer, than the loud and aggressive world of Faerun (where every bandit got +2 swords after a while).
BG2 is a loud and horny teeanger on coke, that fires five ideas in less than ten seconds, without thinking about consistency or even a real mainplot. But you don't care, 'cause the little stories it tells, are pulpy, creative fun.
PoE is more mature and tells at it's core a deeper story, but it loses steam in the middle of the game (which sadly is the biggest part) and you can see, that they had to rewrite stuff and then no time to re-programme it (see the End of Durances Quest). And it's final Bossfight is just lame. The first and third act are still good though and White March shows that there is still a lot of potential for the world and it's themes.
Pillars 1 is that, what BG1 was for BG2: it's rough and they still tried things out, but in it's current state it is already better than BG1 or even IWD1 and 2. I grew fond of it and enjoy my third playthrough, but if PoE2 realises its potential, I will forget it fast, I guess :D.