Treasure Adventure Game ranks as one of the absolute best freeware games to ever come out; one of the best metroidvanias, period. I'm not the kind of person who preorders anything, ever, so it should say something that when I heard of a update/remake of the game, I preordered it. And this is that promised remake. It's very, very good, and I think anyone who likes metroidvanias, or just good action-adventure platforming in general, is going to greatly enjoy it.
It's almost impossible for me to talk about TAW in general without referring to TAG. But since TAG is free and has been out for years, I feel like it's fair to do some comparison:
-TAW has updated graphics, in the sense of hand-drawn-looking 2D art that looks good in place of pretty good-looking pixel art. If that attracts you, I don't blame you, but it's not really what I put stock in.
-TAW has amazing music by the same composer as the original, much (but not all) of which is remixed versions of the old soundtrack. If you like the old soundtrack there's even an option to have that play instead. I found the remixed soundtrack to be very good, with all of what the original had and more. My one complaint isn't about the music itself, but where one particular pair of closely related tracks were placed in the original game really struck me, and the equivalent doesn't seem to be in this one--a weird personal nitpick more than anything else.
-TAW's story is mostly the same as the original's. The lore is fleshed out a little more, details are added here and there, and some things that were just "there" before have been updated to fit in with said lore a little bit better. If you've played the original all the way through, you'll be aware that there are some particularly dark or slightly gruesome things hiding deep inside it; on the whole TAW seems to intentionally tone down and smooth out those things. This is kind of a neutral assessment; personally I liked the darkness and grit hiding in the old game, but not so much that losing it ruins the experience; and anyway it's not ALL gone, I mean the kid still has the hook hand. If you like your games bright and happy this might even be a positive for you. The one part of the game where "fantasy drugs" are involved was also toned down quite a bit for probably similar reasons.
-TAW has similar gameplay, but decidedly improved in some ways. TAG has always been a legitimately challenging game for the most part, and TAW retains that level of challenge but is actually more forgiving than the original, having an autosave you can fall back on instead of having to go back and reload. There's more to collect and do, and it's all pretty fun. Bosses are consistently challenging fights, even if you know the strategies for the original (and in some cases things have changed enough for that strategy to not work so well anymore). I was disappointed with one particularly epic boss fight from the original getting cut up into two different fights and losing a neat aspect it once had, but that's basically the only fight I don't feel was either equally good or improved in TAW. The puzzles and "dungeon"-type locations were reorganized, so even a person experienced with TAG will find plenty of new things to solve and make their way through. The Worst Part of trying to get 100% in TAG (a certain minigame you're required to get a high score on) has been revised to something actually pleasant instead of painful, which I greatly appreciated. TAW retains the trait the original had where getting one particularly important item opens up the entire game considerably, providing five or six different things the player can choose to do right away, which gives a really nice sense of freedom and adventure.
-TAW is very, very slightly less stable than TAG in my personal experience. This is the only true negative I've got, and it's a pretty small one. The issues I ran into were fixed by pausing or, at worst, restarting the game, maybe pushing win-G? Then again, I started playing the beta of the game so even the issues I ran into are probably already fixed while I'm writing this review.
Overall, TAW feels exactly like what it promises to be. An adventure, in a world, with plenty of treasure. A really good one, too.