Alright, played and finished the game this evening. Here's my brief general impressions:
It was quite quick to play through, but I'm rather familiar with the original so there were only a few stumbling points where new puzzles/varied solutions cropped up. Took about 5-6 hours to beat while basically knowing what to do.
The reason it took that long (rather than the 1-2 hours it would take me to beat the original LSL1 at this point) is the stupidly huge amount of interactivity they added to the game. Basically everything on screen has some response to every one of your actions (sometimes quite a few responses) and they're often pretty funny. A *lot* has been added on top of the original game, and it's good quality stuff. There's a bunch of easter eggs to be found if you're observant.
The new puzzles were mostly twists on the old ones with slightly modified solutions, but none of them will particularly strain you if you know your way through the original. In general I thought the modified puzzles were an improvement. The actual new puzzles and new girl in the game are ok -- they rely a bit on... not exactly pixel hunting but very careful exploration and observation, but are for the most part pretty straightforward. They could have been a bit better, but felt mostly in the spirit of the original.
The soundtrack was excellent, assuming you like jazz. Definitely very professional. On the same note, the voice acting was all very good. No complaints to be made there.
The art was mostly good, aside from the sprites sometimes clashing with the backgrounds. The animation is probably the biggest remaining issue, as there's still timing glitches with it, but it doesn't quite range into sloppy territory imo. It could probably use a bit more graphical polish to fix up some of the errors.
The writing is generally on-key, which means it's juvenile, tasteless, often hilarious. Though I found the updated stuff (new descriptions/reactions for existing stuff, I mean) to be a bit better than the brand new stuff. Most of the lines from the original are still there, just with more built on top of it.
That's about it. I'd recommend it without many qualifications for adventure game fans. The fact that they managed good quality on such a small budget and so quickly bodes well for future Kickstarter games. I was fairly sceptical of this for a variety of reasons, but I will give credit where it's due -- Al and Josh came through.
Oh, and yes there is nudity in the game, you just gotta be persistent.