Some things to consider if you're coming to this new:
This is the only album entirely by the original band (I like to think of them as 'Syd Barrett's Pink Floyd'); Barrett was the songwriter; Roger Waters, Rick Wright and Nick Mason generally seemed to go with the flow for the most part - Pow R Toc H is maybe the only properly collaborative track, and reflects the general interest in making music with whatever they could find lying around. Interstellar Overdrive is a severely cut down version of the mainstay of the live set at the time, a sprawling, often disorganised mess which began and ended with a Syd Barrett riff, but generally wandered off into experimental soloing for 20 minutes at a time.
It was recorded literally next door to 'Sergeant Pepper' - at one point, the Floyd were allowed in to watch the creation of 'Lovely Rita'. Strangely, this doesn't seem to have put them off trying to do all kinds of experimental stuff on their own.
Barrett was, by some accounts, pretty much off his face on LSD for the entire thing.
The album does not include either of the singles:
Arnold Layne, which came out first, and was banned in some places because it was about a transvestite who stole peoples' laundry, and
See Emily Play.
The US version of the album is somewhat butchered in order to include 'See Emily Play'; it doesn't include 'Astronomy Dominie' for some reason.
If you're not keen on the hippy-trippy whimsy like 'The Gnome'; fear not, it hardly ever comes up again.
It's so definitively of its time that it's very hard to review it dispassionately from 50 years away. I may have been alive when it came out, but I was buying Pinky and Perky singles, not Pink Floyd albums. When I did eventually hear it, I didn't much care for it, because it didn't really sound like their other stuff. Now, I can appreciate it (I like 'Bike', for example, because it seems to sum up Syd as he was at that time, but it takes a bit of determination to wade all the way through side two to get there.) but it's not the first place I go for some Floyd.
As I will no doubt demonstrate, I like Floyd best when they're stretching out and exploring musical ideas, so in the couple of places here where you can see them trying that stuff, I think it works much better than in the 'let's make a quirky, psychedelic three minute pop song' stuff.
We're not quite done with Syd Barrett yet, but this is the only Floyd album which is pretty much his idea of what they should sound like. It's not exactly representative of what they would become, but it's a pretty good representation of what 'psychedelic rock' sounded like in 1967.