Installed and slapped legionaries and brigands for the past couple minutes, and so far I'm definitely entertained.
The aesthetics, while a little too clean for my taste as well, do their job in the context of a 2D side-scrolling beat 'em up, the animations (Obelix' signature belly bump, the grab-hold-and-rapidly-bitch-slap or the grab-and-overhead-smash-from-side-to-side) are just like I remember them from the comics and the 80s animated films, and the core gameplay loop is exactly what's to be expected from a game that has "Slap them all!" in the title.

Localisation (German in my case) has been decent so far (the voice actors are no Frank Zander and Wolfgang Hess respectively though), but the music, while fitting, is way too much in the foreground, drowning out the sound effects considerably and making them sound flat and lacking in the oomph department.

Which is only further exacerbated by the puzzling absence of separate volume sliders for the music and the sound effects, respectively. In fact, there are no actual options under "options" at all.
Instead you're presented with the "tutorial", being able to watch the introductory opener (the well-known bit about the whole of Gallia being occupied by the Romans except for that one village) and the ending cutscene (after having played through once), the "credits" and being able to go "back" to the main menu.
Also no key rebinding (time to break out AutoHotkey again), no graphics options, no nothing. Very, very disappointing in this regard.

But again, if you can see past these (hopefully just temporary and soon-to-be-fixed shortcomings) you might get entertainment out of this nonetheless, especially if you're familiar with the franchise and/or can't take off those nostalgia-tinted glasses.

Loved the comics as a kid, great to see a modern game on the subject!

Amateurs! :P

If you continued to play, is the game still as entertaining after a couple of hours?

Yep, still haven't gotten tired of all the slapping yet, but didn't progress that much further either (the hardest difficulty is aptly titled and I just made it to Britain).

Not sure if I'm the right person to ask in this regard anyway, being that patient, forgiving and shrouded by nostalgia.

I was put off by the graphics at first, or what I saw of them in the screenshots, but if the game is fun to play, I can give it a try, especially since I am in love with the comics and the animated films since my childhood, and quite forgiving too.
Anyway, thank you very much for your answer.

Sounds like a pretty fun game. It looks like we are playing a game on cartoon.
It looks like a game straight out of a cartoon or a comic book.
It's really reminiscent of style of the original comics...