Preliminary: I didn't like the movement or platforming of the first one, but uh, this level select screen and its music bodes well 
Wow great music for the Crystal Castle stage. And this feels like an actual Castlevania game (so far) unlike the first GB one. The well-placed whip smack makes me happy :) I do wish the Castlevanias would update their jump mechanic, but this is surprisingly solid so far.
Day 1
They really seem to load you up with special attack weapons in this one compared to the others! And the Axe and Holy Water ones too, which are nice. I do wish I moved faster, but other than that, this is really promising. I can only imagine how great it felt to have Castlevania in your pocket!
Nice! You can turn and attack while on a rope (and the rope mechanic is better than the mainline Castlevania stairs mechanic up to this point >.<) And you can hit away most enemy projectiles which I always like.
Pro-tip: when dealing with those pesky spike walls, and in general, you can zoom down the ropes much more quickly by holding the jump button as you press down. Love that I found that out on my own, love an intuitive pick up and play game, and Castlevanias are particularly great at that! Tho gosh this guy is sluggishly slow.
Darn this whole time I was keeping my Holy Water, ignoring all the Axes I found, and now I get to the Crystal Castle boss and feel the Axe would've been better cuz the boss floats :-p Cool that there are bosses and enemies unique to this game! Figured they'd just be rehashes of the mainline games.
Wow I can't put this down like with the first Castlevania. Tho I really am going to after this second stage cuz I wanted to do some active Ironman playing on OSRS. This really just keeps impressing me. The controls feel much more like the NES Castlevanias than the messy first Gameboy Castlevania. Relatively tight and some QoL features like the rope mechanics rather than stairs. I really liked the spider enemy mechanics too. Ok time to finish up this level and call it for the night.
These first 2 bosses were quite "easy" but in a good way. I'm really digging this so far. And I suppose they aren't "first" but I did Crystal Castle and Plant levels first. Wow and I just peeked at the next level I'm doing (Cloud Castle) and wow. Another great tune! (I also am grateful that special weapons and whip upgrade etc carry over between levels, but you restore your health. How forgiving for a Castlevania game!) And to think my next game is FF4 which I'm excited for as the first SNES FF. Then Legend of the Mystical Ninja, which I've always been curious about. Then the sequel to the Bonk game I loved! Ah! 1991 is perking up!
Ugh I just can't put this away! My poor neglected Ironman lol. The dark segments are rough in this, but it makes sense--I was being greedy getting the big hearts, and without any candles, of course it's dark! Haha.
Day 2
Still just absolutely loving this. Proud that I came up with my own solutions to the enemy mechanics like the ones that jump back and forth throwing swords at you. I wasn't able to take many screenshots but the Look was honestly impressive for a Gameboy game

Ok that dragon snake thing that came from the ceiling and wall was super hard. Otherwise the bosses had been very doable. I had to abuse savestates at the start and even in the middle of the battle to succeed heh. Fortunately the death mechanic is reasonable but I only have an hour to game tonight and I'd love to see the final 2 bosses tonight!
Unfortunately the Dracula's Castle tunes so far have not been as good as the earlier songs. Still, overall an excellent game so far. Possibly even a Favorite! Oh me and Castlevanias... The buildup segment to the final bosses, though, were great tunes and great Look
Ok the last area bosses are obnoxiously hard ngl. Maybe there's a way to cheese them but I tried playing this without a guide or anything. Argh. Looks like savestate abuse it is. I finally beat the Belmont Son boss guy! Gah that was hard! It helps that I got better at dodging the swords. My hour is up sadly but I may get a bit more time later to play. I assume I go straight to Dracula? Or maybe there's another whole area gah.
Great look for this final stretch tho 
Ok returned to it now and yea. How. Definitely abusing savestates for Dracula. And at last. Gosh the number of times this castle has been destroyed! lol.

Ok sheesh the text goes on and on lol. But still, a nice ending screen and jingle.
Look: 8.5/10 Some particularly good screens, otherwise just classic and good Gameboy Look.
Sound: 8/10 Decidedly better than most GB games. Got a bit meh at times but for the most part very good and the other tunes may grow on me.
Play: 9/10 Good ol Castlevania fun. It got a bit too hard at the end for it to earn the perfect Play rating that some other Castlevanias have, but it really is excellent for a GB Castlevania. Great work with the enemy mechanics and unique level mechanics like the up and down ropes.
Feel: 9.5/10 Good ol Castlevania, finally properly brought to a handheld console.
Attachment: 9/10 This surely made the list of Castlevanias I will replay again and again throughout my life.
Overall: 8.8/10
Completion: Main Story
Playtime: ~1h 45m (largely thanks to abusing savestates for final 2 bosses, otherwise who knows how long this would've taken me lol)