In case the context helps, before Dawntrail, I wrote this about BLM:

BLM definitely has a great cohesive design; it's a class about managing resources (mana, time, charges, procs) while under numerous types of time pressure (elemental countdown, polyglot countup, Thunder countdown, and of course encounter mechanics). Thus, it doesn't really have a "rotation" in the same way that most other classes do, but rather has a priority system, where ever-changing context thoroughly dictates the spell or ability that you should cast next. And that "should" is very ambiguous, because some casts are more risky than others; so without absolute knowledge "should" can err either towards safer play or more risky play. This is because BLM's cast times under time pressure mean that more than any other class, BLM's "rotation" is capable of being disrupted by mechanics.

There are many classes where for the most part or entirely, what's happening in the fight doesn't meaningfully impact what you're spending your GCD on. One of your hands is devoted to making sure you're in the good locations and not the bad locations, and the other hand is doing your rotation, and rarely do the two ever meet. Not BLM! The appearance of an orange tint underneath you doesn't simply mean you should move, it means you need to reevaluate your plan. Maybe that means you need to interrupt a cast, maybe it changes the next few spells you were planning on casting, or maybe it means you strategically decide to soak the damage. It all depends on the precise context, including your timers, and the faster you can make an accurate decision the more optimal your play will be. And that's what I personally love about BLM: that I am constantly calculating new plans based on more factors than I can comfortably fit into my head. Every moment feels fresh, each a chance to either make a mistake or somehow keep all my plates spinning and optimize better than I ever have before!

BLM's non-linear structure keeps me engaged. I will never be as good with BLM as I am with SMN, but that's a small price to pay for fun. And every time I play BLM, I get to have fun. BLM presents me with challenges that make me think and react in ways that other classes don't. When I do pretty good with BLM, that is so much more satisfying to me than when I play a perfect game with SMN. I will never be optimal with BLM, but that's what makes it fun: every time I play, there will always be room to improve, I will always be able to play better than I have before. And that's engaging for me.
Since Dawntrail dropped, I've been playing BLM with the intention of loving it. When I've felt uncomfortable with an adjustment, I've tried to keep an open mind, seeking out different ways of thinking or playing that would make things "click" and feel good. To this day I'm still trying to find solutions to the parts that don't feel great to me, and I'll keep trying. But I do feel like I've put in my due diligence and am ready to provide some feedback. I want this to be constructive feedback, so I'll do my best to explain me thoughts and feelings.

Flare Star
Once I reached level 100, BLM became all about Flare Star, and that has resulted in a less enjoyable experience. Every Fire Phase feels more rigid and stressful now, because if I can't cast 6 Fire IV's, then I don't get to cast my biggest spell. And with all the movement required by many boss encounters, it generally feels like there's next to no wiggle room if I ever want to cast Flare Star.

Before Dawntrail, a Fire Phase where I missed 1 or 2 Fire IV's felt reasonable; there was room for improvement (which I would happily chase), but overall it still felt like I did "good enough". But now the difference between 5 and 6 Fire IV's isn't just 1 Fire IV, it's also your Flare Star. Not only is that a much more significant damage loss, but it also means I don't get to push the big button. That feels bad.

In fact, it feels so bad that even when I do get to cast Flare Star, it doesn't feel good; rather than feeling joy from casting Flare Star, I simply feel a sense of momentary relief that I made it through a Fire Phase without feeling bad.

I think this would be pretty easy to fix: just make it so that the Astral Gauge doesn't empty when players enter Umbral Ice. That way even if a player has a sub-par Fire Phase, they don't feel like they have fallen so far behind, and they'll get to cast Flare Star towards the beginning of their next Fire Phase. The difference between a delayed Flare Star and a dropped Flare Star will mean the world to players who haven't yet reached that degree of perfection.
No Thunder Procs
I miss Thunder procs. At present, Thunder is just a normal DoT; you want to keep it active to optimize your damage, and that's that. But before, Thunder felt great. I really want to emphasize this: pre-Dawntrail, the biggest reason I wanted to keep Thunder up was because every tick of it gave me a chance to get a Thunder proc, and casting a Thunder proc felt good.

And beyond feeling good, Thunder procs added a degree of dynamic play to BLM. Whatever you were already planning on doing, once you get that Thunder proc you suddenly had a new option to consider. And that kept players on their toes and made every moment with BLM a bit less predictable and a bit more dynamic.
Umbral Ice Mana Gain
Personally, I really like this change; before Dawntrail, I would often be unsure whether my mana would actually tick back to maximum before my Fire 3 cast finished, and it was a bummer in the rare case where it didn't work out properly. Now I know for certain that if I cast Blizzard 3 and then Blizzard IV that I'm going to be topped off and ready for my Fire Phase. I like this reliability.

It sounds like the devs have already acknowledged that there are issues with this system at lower levels, so I won't talk about that; looking forward to the solution, though.
Manafont
I like the new Manafont; with a single cooldown ability, I get to start a fresh, perfectly-prepared Fire Phase. It's a simple and effective concept.

Thanks for taking the time to read my feedback; I hope that this can help shape BLM adjustments in the future!