Preliminary:
I know it must just be me and not having played the first Super Mario Bros for a bit but the momentum and mid-jump-change-direction controls seem different from what I remember. Rare that I do this in a Mario, but since I totally don't know these levels, and they're infamously hard, I'm not just running all the time! Didn't like my first taste of a Bad Mushroom but I was getting along just fine. Plus I was playing as Luigi! (Ok, maybe later in the game I started running a lot of the time lol)
Look: 7/10
I mean, it's exactly the first game, just new levels right? I will be saying this a lot in the review, but it's like those fan-made super-hard silly levels people make
Sound: 7/10
Again, it's the original. And the ending song wasn't particularly good either.
Play: 8/10
Ohhhh maybe some of the quirky-feeling controls, considering it wasn't that long ago that I played the first Super Mario Bros, is that I'm playing as Luigi. Regardless, some of the mechanics are outright clunky, like a couple times I jumped off a bullet that I clearly was hit by etc. One definite thing, like with the first Super Mario Bros though, is what a deliciously responsive jump button! No matter how clunky the momentum was in that moment you could almost always still fit in a jump!... even if the momentum/direction wound up not where you expected ha
Lol those trampolines in 2-1 (I accidentally got to a level warp, I had a tendency to do that in the first Mario and they had it in the same cave 1-2 level! woops!). You jump up in the air for some ambiguous amount of time then suddenly drop down. A lot of this seriously feels like fan hacks tbh. And lol that you can jump over the flagpoles, did that happen in the first game??? Feels really fanmade-ish. (And indeed, the trampoline mechanics exploits in later levels like 4-3 were just awkward and remind me of microcomputer/speccy/c64 platformers where they have toexploit a quirky or faulty mechanic to add difficulty).
The collision masks of the Fire Bars is super messy and they clearly want you to learn them and exploit them (like C64 amateur programmers used to do). Like, at some angles/spots, the Fire Bars get ya, but if you duck in a corner despite 2 full fire balls being in your sprite, you don't get hurt lol. And you need to know this to get through certain levels. Classic platformer antic, but silly for an NES game. Nintendo certified usually has a higher quality than that.
Feel: 7/10
Lol! I was so proud of finding the Warp Zone in 3-1 but then realized it's back to World 1 >.< (3-1 was such a short and silly level in its normal form...) And now I gotta deal with a water world without Fire Mario (which the water mechanics are still so bad lol especially the momentum factor/dropping down/bouncing off things) . Annnnd now a Castle/Bowser without Fire Mario >.< Gr. 3-4 apparently is one of those levels where you have to go the "right path" to move on properly, never was a fan of those "secrets" in the first Mario Bros. I had no interest in figuring it out myself, especially with only 2 lives left and just a Big Mario. The fact I went straight to looking up the path isn't so positive for how much I was enjoying the game: I do really love the first Mario Bros and was having a lot of fun with this too, felt like a continuation from where it left off, but the levels just felt... silly? Amateurish? Something. (Well, the 3-4 Bowser wasn't bad as just a Big Mario, but still...)
Attachment: 7/10
Woops, accidentally warped from World 5 to World 7. Unlike the original Super Mario Bros, I didn't feel the need to replay to see all of the levels though--it had nothing strikingly new from the first game and had some goofy level designs. Ironic, though, that the good warp, that skips to worlds, was easier to find than the "bad warp" that brought you backward that I stumbled upon (luckily they had a fall in there so you could kill yourself instead ha)
Ohhhh, yea I just read up: Luigi has a higher jump but has worse traction. Makes sense! I should've played as Mario >.< lol. Then it would have matched the first game better. Meh. Wait omg I just read there are 13 worlds?! That's too many! (Oh, phew, I read on Wikipedia it's only 8, so I'm almost done).
Lol at 7-3's odd use of the awful trampoline mechanic in this. So illogical but luckily didn't take long to figure its illogical nature out. Ugh, I was going to say how I love moments like these--coming upon secrets based on the usual mechanics of the game--but nope. The utter pettiness. I got up here, which should always mean access to something cool or at least skip through the level but nope. You just reach the edge of the level and can't move on... so had to wait for the timer to go down to die. If only could go backward... Lame. That had to be intentional design too
I took a break for the rest of the night after that frustrating moment haha. Welp, replaying it, luckily stumbled upon a Big Mario Mushroom. Not a fan of how much they use the faults of the first Mario in this. Again, it really feels amateurish, can't believe this was a legitimate sequel while Zelda 2 and Castlevania 2 made such bold strides as sequels this was just like the first Mario but as if it had been a C64 platformer. Sorry C64 purists, but I look for more, or rather a different quality, in my NES platformers. God the rest of this level would've been so much easier as Fire Mario ha, but nooo I had to go up there. But bam! I made fast work of the stretch before Bowser and ran under him as he jumped and finished him off immediately. Now that's that classic Mario feeling I want more of.
8-2 did start to have a unique/interesting look, at least. And I do like how that secret worked, reminded me of Super Mario World style secret. No spoiling :-p It's actually doable. And lol the final Bowser was a joke as per usual, I was even a small Mario because I had accidentally ran into a fire projectile from Bowser Brother or w/e.
Oh wait, so there are 13 worlds?! Just 4 of them are secret?! Well, because I used a Warp, I guess I don't get access to them? And tbh, that's fine with me. Neat secret though. 
Not one I plan to return to, but it's still that classic Mario gameplay I can't deny I love. Even as frustrating as it was. Felt like a C64 amateur programmer was given Super Mario Maker back in 1986 ha. Again, though, still can't deny my love of Mario gameplay. I'm a sucker for it.
Completion: All 8 regular worlds, 527300 Score (I only had one life left for the bonus at the end ha)
Playtime: ~1 hour