Ok 3 points I'd like to discuss:
Have we improved over last season? IMO just barely, not that much of an improvement, but an improvement nonetheless. I don't know how Wenger expects us to improve when he doesn't address our weaknesses in the transfer market. Giroud isn't suddenly going to become a world beater, Mertesacker isn't suddenly be able to run faster than my grandmother, and Flamini isn't suddenly going to start looking remotely like a professional footballer. I love my team, and I watch every minute of every game and do not miss it for anything, but it has got to be one of the most frustrating teams to support in the world. The potential we have, with our finances, our stadium, our fanbase and all those success factors and we keep failing and doing it the same way and for the same reasons every year is just infuriating. The only reason we're still in the race for the title this season is because the competition in the EPL has been extremely poor.
Do we have a chance against Barcelona? I think they are the favorites for the CL, I think we are exactly the kind of team they enjoy playing against. You need to be very good at defending as a unit, very quick on counters, and extremely efficient with your chances to stand a chance against them, and while I like our counterattacking football the past two seasons and think we have very good counterattacking ability, we fall short in defending as a unit and in being efficient in front of goal. So while I'm sure we might cause them a lot of trouble at home, the latter two factors will mean we don't stand a chance at the Camp Nou.
On Coquelin and Koscielny: I like both players; Coquelin does a good job for us, he's very energetic, he's an excellent tackler, he breaks up play well, and in general his performances have been very consistent over the past year or so. It's still too early to judge him, because he suddenly burst into the scene and this could all be due to him being very grateful for getting a chance to play regularly at the top level, but if he continues these performances I think Arsenal should be very happy with him; our problem is not having any cover whatsoever for him.
Koscielny is our only decent defender IMO, he's not a world beater in any sense, he does make one too many mistakes with his positioning, but he's excellent for the high line we play and he's one of the fastest CB's in the world IMO, which gives him a big advantage in the EPL where spaces are open and pace is extremely important. The other two are our problem; Mertesacker and Gabriel.