I am really liking the trade dress/page layout and colors of this book! Very, very cool and beautiful.
Something I really want to know is what is up with the Bladesinger in Tasha's Cauldron of Everything; I actually just started a new Bladesinger character not too long ago, and I would really really like to know if the Bladesinger printed in this new book is going to be a new altered version, or if it is just going to be a reprint of what was in the Sword Coast Adventurer's Guide.
I absolutely adore Bladesingers and have been waiting for just the right opportunity to play one ever since SCAG was released, and when the DM (my brother) suggested that I use the opportunity of the new side-campaign he was beginning to finally make one, I eagerly jumped at the chance (with the added authority of the DM's recommendation!) I just hope they didn't do something dumb and weaken them for some reason; I think the version in SCAG is just about spot on.
I am also extremely curious as to what new Feats that will be included in the book; I am always hungry for more Feats. I am hoping that they include finalized versions of the weapon mastery Feats from the Unearthed Arcana article a few years ago. My brother fully allows these Feats in his games, and I especially love the Blade Mastery Feat; it gives a definite mechanical bonus to make a character legitimately better with swords than with other weapons, making the character an actual blademaster, and I love how the Feat is designed to illustrate the fact that swords are flexible weapons good for both offense and defense. based on whether you assume and offensive of defensive stance. I have already had two characters with the Feat; my brother actually thinks the Feat isn't that powerful, only providing a +1 to hit and a +1 to AC by giving up your reactions for the round, but I love it primarily for roleplaying reasons as it makes your character a legitimate sword expert.
(Another reason why I love the Blade Mastery Feat is because it basically reproduces the benefits of the original Bladesong Fighting Style from the AD&D 2E Complete Book of Elves, which originally introduced the entire concept of the Bladesong and Bladesingers. The Bladesong Fighting Style was something that any Warrior or Rogue could learn by spending several Weapon Proficiency Slots, in case you just wanted to learn a form of the style to fight with but you didn't want to dedicate your whole life to the full Bladesinger Kit and become a lifelong champion of the Elven race. The basic Bladesong Fighting Style cost two Weapon Proficiency Slots and gave you a floating +1 bonus that could be used for either attack or Armor Class, switchable from one option to the other each round. But if you spent a third Weapon Proficiency Slot on the style the floating bonus increased to +1, and you could either use the full +2 bonus on attacks or AC, or you could split it and gain +1 to both. The Blade Mastery Feat duplicates this bonus by giving a +1 to hit with swords, and either a +1 to AC if you devote your Reaction of the round to assuming a defensive stance, or you can instead assume an offensive stance which gives you advantage with any Opportunity Attacks you make with your sword during that round. Because of all that I consider the Blade Mastery Feat to represent training in the Bladesong style when taken by an Elf character (and representing some other equivalent form of advanced sword style for other races,)
I have already given my new Bladesinger PC the Blade Mastery Feat... so if Tasha's Cauldron of Everything includes both a revamped version of the Bladesinger Arcane Tradition and also an altered/finalized version of the Blade Mastery Feat then I am going to have a fair bit of adjusting to do to my character... which is actually something that I wouldn't mind very much, unless it turns out that they made some kind of drastic depowering to the Bladesinger.
(Finally, as an aside for anyone else who also loves Bladesingers; have you ever heard of the term tachikaze? It's a term from Japanese swordsmanship and literally means sword wind. It refers to the swooshing sound a sword makes as it cuts through the air, and proper sword technique can be determined by the sound of the tachikaze; if you make a proper swing it will sound a certain way because of the angle of attack of the sword cutting through the air, but if you make a poor swing it will sound differently. Therefore astute sword masters can tell how skilled a swordsman is just by listening to the sound of their sword swings. Nihonto (Japanese sword) smiths even developed a certain type of fuller to carve into the blade to augment and accentuate the sound of the tachikaze to make it more audible! (Which is now something that I envision Elven swordsmiths doing on high quality Elven blades.) I had actually never even heard of the term tachikaze until just this very morning wheb I randomly stumbled across it, but I was of course familiar with the idea of swords making certain sounds as they cut through the air... in part because it is the entire basis of the name of the Bladesong fighting style. So, for any other fans of Bladesingers out there - there is absolutely a real world basis for the special whistling sounds that the Bladesong makes!)