Super-solid simpler hori; fans of snarkier cute 'em ups like Hana Taka Daka and PC Denjin will love the aesthetic. Lots of bulging eyes and sweatdrops, as you unload on the gurning fiends.
Copying over my posts from the venerable
shumps ticker thread - as noted below, your choice of autofire makes quite the impact on difficulty, though not in the "raw power" way typical of stuff like Raiden or Darius Gaiden. The "AutoL1" button lets you keep maxmimal firepower onscreen with perfect timing, while plain autofire [rapid shot + charge shot] is quite a bit more involved, and no autofire at all moreso.
That said, AutoL1's genuinely lots of fun! I'd almost consider it a case of Beginner and Advanced ship types, both are worth trying. It's easily worth its ACA asking price, imo. The best sort of cute 'em up, tons of style supported by a no-nonsense chassis.
If you love cutesy horis, but demand intensity, NMK's
Hacha Mecha Fighter might be a better alternative on ACA. Just know that it's wicked hard, despite the wonderfully sunny/surreal
ANIMAL SENKI aesthetic and instant pickup+playability! The moderate ship speed and hitbox won't alarm at first, but as early as Stage 2, the Rank will go nuts. Bullet speed is brutal, and death is perpetually a split-second's hesitance away. It's not all cruel - you have a really nice Gradius-style Option dragnet, which can counter enemy formations interestingly, and as usual with NMK, bombs are plentiful and strong. But it's definitely one of the most harrowing-yet-cute STG experiences this side of Parodius Da.
NO REFUGE ^_~
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Latest ACA release, Namco's
Pistol Daimyou no Bouken (1990). Had never heard of this one - pleasantly surprised. It actually reminds me a lot of the PC Engine's later "colourful character STG" niche - Coryoon, Hana Taka Daka, PC Denjin, etc. Big yet smartly-proportioned sprites, and simple, snappily responsive action. You've got a straight rapid shot, and a lobbing charge mortar with two levels, serving as both heavy bombardier and anti-air counter.
As is Hamster's wont, the ACA version makes a small but keenly insightful addition: autofire L1 charge shots. This really improves the game, imo, effectively giving you a dedicated second attack button, and freeing up braintime to focus on dodging.
Difficulty seems mild-to-moderate, in the five initially-available stages. Clear three to unlock the last, just seeing about that now. Ala Darius, lower=harder, with the fifth's raid on GAIJIN TOWNE boasting some superbly tight foot-to-floor action. ala Metal Black's second stage, or R-Type Delta's fifth, while there's no terrain per se, the smart use of juggernauting obstacles fills in more than adequately.
st5.3 = The FIRELEO and MUJAHID Show 
Tonally, fans of Ganbare Goemon (particularly the second SFC game) and Keio Yuugekitai will love this. Pretty sure I took out a Moby Dick-riding Cap'n Ahab en-route to the source of the Black Ships. Closer to Nihon, lots of kappas and youkais to put down hard. Apparently the player character was originally a boss character in Beraboh Man, which I've never played (something it wouldn't surprise me to see ACA address). I'm surprised he never got any followup attention, given the obvious production values and talent behind this game.
A quality simpler hori, worth a punt if you dig its colourful niche. Here's hoping some more under-repped early 90s Namco STGs will show up! Metal Hawk, Fighter/Attacker and NebulasRay would be good.
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Just finished Pistol Daimyou's unlockable sixth stage, which I suspected might be A Trip To Hell, given the considerable upped intensity of the lower two routes. But nope, it's just a moderately demanding miniboss rush, and a last boss who isn't much either. Started over sans autofire - I think I might try for a first 1CC this way, actually. The auto L1 shot is great for a training wheels run, illuminating exactly how powerful you are; manual fire can appear worryingly under-egged, at first, when you don't know to keep chuckin' those small bombs at the oncoming crowd. But its relentless, frame-perfect stream of bouncing mortar death really is a huge leg up.
(pre-ACA, Pistol already bore the HG101 "WAHHH ITS IMPOSSIBRU" - read: "This is notably substantial!" - seal of approval. I know better than to think it'd have received a more realistic appraisal, had the scoundrels been rocking ACA's AutoL1 - but it should've!
)
This said, AutoL1 is a lot of fun, enabling much cockier play than regular autofire - less the typical brute DPS supercharge, more of a "driver's assist." It's a naturally entertaining weapon, with its beaning trajectory and bubblewrap
*PON* feedback - innately satisfying to nail bastards with, whether from across the screen, or pointblank right up their jaffers. Going without it, I find myself using the rapid and L2 attacks more spontaneously, even if L1 barrages are basically as doable by hand.
AutoRapid bussin VS AutoL1 bussin 
if you know your ass from a hole in the ground WRT STGs, expect AutoL1 to see the 1CC off in a couple evenings at most. If that's a kiss of death (for shame! :O), consider going with plain [rapid shot] for a significantly tougher (though still relatively easy) time. Otherwise, enjoy the violence.
)
Besides rapid shot autofire, ACA Pistol has a dedicated frequency for Level 1 charge shots. This is incredibly useful, since not only are L1s the happy medium of speed/damage VS crowds, they're also a valuable anti-air attack.
Still not great, especially against the blue sky, but not quite as dire as I'd recalled.
Hacha has that Trigon "Already Dead" step, where moderate ship speed, large hitbox, and vicious bullet velocity make getting caught flat-footed anywhere up to a half-screen away potentially fatal. Nothing like seeing a fucker open fire and hitting the stick, only to eat HIT JUDGMENT on the last pixel of your hitbox. 
I cobbled together the semblance of a plan before making a go of things. I know you can easily choose a Frost Giant or an OG Sphinx as your second opponent, depending on how quickly or slowly you take out the opening Big Black Jerry. (bomba for Frosty, no bomba for Sphinxy)
but thought I'd record, just in case I'd stumbled over something. 
) The later stages where visibility is mostly in check, particularly 
