I've had a bit of time to reflect on this, watched the pilot a few times to really get a grasp of it, and re-read the section of the comic this adapts. By now, I've come to terms with my overall feelings and opinions towards it.
The Homestuck pilot is a pretty bad 1:1 adaptation of the source material. It rushes far too quickly through things, drops gags left and right in sacrifice of getting through the material faster. It, for whatever reason, introduces more swearing into the characters' dialogue, including in lines that are directly ripped from the comic - they just threw in "fuck" there to add an extra punch. It emphasises action in comparison to the source material, and strips out some of the more interesting parts - no Haunting Piano refrain, the narration scene where John looks out onto the neighbourhood is cut short for a gag, etc.
In spite of all this, I think it's a good pilot. I think Homestuck Act One is fairly dull, largely dragged out, and makes for a poor material base to adapt off of. Homestuck's early acts find strength in kinda how long things take to play out, there's a steady build up of introducing characters as it goes. A big change here is the fact that John refers to Rose, Dave, and Jade as their names instead of handles. Their names aren't even revealed till much later, with Dave and Jade's names not even appearing until Act Two. This makes a bad basis for a pilot - trying to have characters show up, be spoken to directly, without even naming them or showing their faces, is just a hard thing to pitch to companies looking to adapt this work. Homestuck's comedy and slow build-up works well in a text format, not so much in the audiovisual medium.
There are still obvious faults here in this pilot. It's good, but not great - many things are oddly unexplained, like John's captchaloguing of the smoke pellets and Colonel Sassacre's book. The smoke pellet scene after the strife with John's dad makes way less sense in the pilot than in the comic, because you aren't ever explained what those little purple things even are. This is just a single example, but there's just a lot that sort of just happens without any form of explanation. This is fine for me, because I know the material, and I know what's going on. For a newcomer, this is fairly obviously confusing, you've got content being thrown at your face without any good explanation. I do hope that in a full series, they slow things down a bit and explain things more. This is clearly a pilot to me - not a first episode, this is just trying to get the idea across to adapt it into a full series. The 11 minute runtime here is not helping the pacing issues. The swearing is also completely excessive, John just simply does not swear nearly that much in the original. It's out of character, and frankly a bizarre writing choice that I can't fully wrap my head around.
The strength of the pilot is purely that it's entertaining to watch. It's got a good grip of captivating the audience, and its animation is very flashy and stylised. It captures the effective mood of a lot of the later parts of Homestuck, just not so much Act One in particular. The choice to make Wayward Vagabond appear immediately is also quite smart and does a good job of streamlining future events. A lot of Acts One and Two happen mostly in parallel, and in the medium of a TV show, you can do a more effective job of just swapping between these parallel settings. I think it's good, but I do hope a finalised product is more polished, and does better jobs of explaining events. Much of Homestuck's content relies in the density of information presented to the reader, so skimming over that content and only visually presenting it is not the ideal move, in my opinion.
I do fully hope this is adapted into a full series. I do think the team working on it at Spindleroo genuinely cares about the series, and wants to do their best job at giving it justice. It will remain to be seen how capable they are of doing that. Either way, if you're an existing fan, I'd give it a watch, and if you're a newcomer, I'd genuinely recommend watching it twice if you're confused, and things will make substantially more sense a second time around.