Yes, they're good, but to reach the next level I think Arsenal need to improve in that area. When compared to Vidic/Ferdinand, or Terry/Luiz, I think Arsenal's defence is still lacking slightly. From what I've seen (you may be more knowledgeable than me about this, I don't watch them every week) neither centre back appears to be particularly commanding or shows lots of leadership. Other teams challenging for the title have more experience and leadership at the back I feel. Against Barcelona, you were camped in your own half for most of either leg (I'm not saying this is a bad thing at all, I feel it is the way to play against Barcelona. Added to this I also wanted Arsenal to win, so I look favourably upon their performance

) and the defensive midfielder in either leg offered a lot of cover to the centre backs which made their night marginally easier. Still an impressive performance though, but one good match can't really tell us much about the standard of the partnership.
Neither CB is particularly commanding, no, but the whole team has a good understanding & we generally don't sit back and try to soak up pressure like Utd did yesterday so there's not a whole lot of point in them being commanding a lot of the time. If we're under pressure, they have a good understanding, cover for each other and defend as a unit. At the start of the season there was communication issues all the time - At the Stadium of Light for e.g. Clichy kicked it against Kos and Bent tapped it in, + we conceded a lot of goals from set pieces, but that's improving and Szczesny isn't afraid to shout (I'm ignoring the howler against Brum).
I don't think we were camped in our half at the Emirates, we let them have the ball and they did jack all with most of the time - like Utd did to us, but we weren't trying to contain them and park the bus like we did at the Camp Nou.
You can look at their defensive record, but it doesn't tell everything. Arsenal obviously have far more possession than the opposition, which I think is the major factor behind the lack of goals conceded, rather than the centre backs. I just get the sense that errors are not too far away when the centrebacks are present, and that they don't completely fill me with confidence.
Arsenal have most of the possession, but especially from counter-attacks, there's always a danger of us conceding and both CBs cut out a lot of passes and are perfectly adept at making last ditch challenges - see Barcelona games for the perfect example of this.
I think you're making generalisations based on players like Squillaci, and the performances of Koscielny at the start of the season. Defence isn't our issue, IMO - Yes, we could do with a Tony Adams or a Sol Campbell to lead from the back and generally be a rock, but in terms of raw defensive ability, I'm confident our top 3 CBs can do the job when not injured.
We might disagree on Bendtner then. I just don't rate him as a forward really. I think RVP is an exceptional talent when fit, but there aren't many suitable options otherwise. Chamakh is a good Plan B when Arsenal want to mix it up a bit, but I think they could do with another player more suited to their style when you consider RVP's unfortunate injury record. I might be getting ahead of myself, but I think a big signing up front (Fabiano? Benzema? Nilmar? Okay, most are terribly unrealistic but you get the gist

) would do wonders for Arsenal's game.
Nono - I don't think he's up to the level of RvP, but he's an important player because of the knack of scoring important goals and bringing something different to the side, whether it be a little trick like against Ipswich in the CC Semi, or a header against Stoke. He's not as bad as everyone makes out is all I'm saying.
None of those 3 will happen - Benzema is finding form, Mou won't want to sell another ST when he's been struggling all season with not having enough and only has Barndoor as a replacement for Higuain.
Nilmar is just completely unrealistic, he's not the kind of striker Arsenal would look at and thrives in a league that isn't really that good.
Fabiano has just gone to Sao Paolo, and a big Target Man isn't exactly Arsenal's style.
Fabianski is inconsistent. No denying that, he's made some horrendous errors in his time in front of goal, and has picked up nicknames accordingly. Real problems handling crosses which means any delivery close to the keeper is a threat. Having quite a few disasters and letting in dreadful goals makes him inconsistent by my reckoning.
Fabianski was straight up poor most of the time before this season, then he came in for Almunia, made a mistake vs Newcastle and Spurs (for which he was replaced in the CC by Szczesny) & then came into real form and was brilliant. I don't think it's inconsistency, but going from poor, to pretty good over a season given time and help, and the threat of Szczesny pinching his spot.
You've accepted Almunia isn't consistent, and I agree on that.
Yup.
With Szczesny, I've probably been a bit harsh. Maybe inconsistent isn't the right word, as he hasn't had enough time to prove himself either way. Time will tell whether he steps up to the plate and recent performances have been encouraging - Birmingham game aside. I just think it's placing a lot of faith in an unproven goalkeeper at such a high level to expect him to reproduce consistently impressive performances at the moment. Fair enough Wenger wants to develop him as a player (which I admire - it's good to see managers trying to bring new players though) but for a top club you'd expect there to be another high quality goalkeeper to share the burden. Akinfeev strikes me as a decent target.
It is risky, but I think a player like him thrives in big games, and when he's under pressure. He was superb at OT in December, then at the Emirates vs Barca, when everyone was wondering whether we should give Almunia the shirt on a temporary basis.
You do have a point about sharing the burden - it's not what most people say tbh, a lot of people assume it's Football Manager and we can just buy Adler for £20m and be done with it. Akinfeev is unrealistic as well, he'd cost too much.
It will be interesting to see who AW goes for on an emergency loan
Anyway, I'm off now so won't be able to reply for a while. If you fancy replying I'll try to get back to you sometime tomorrow. The tone of my reply will depend on a certain rugby match!
ENGERLAND!