I've been playing Primus songs for about 17 years now, so I'm likely as qualified as anyone to break down Les' style. Please note all of my comments are being made as a person that's loved this band for about 25 years, have seen them over 10 times, and learned most of their catalog up to 2002 by 2003 or so.
Les is a divisive bass player because he specifically has developed a style that is incredibly unique, but flies in the face of conventional playing.
His strumming technique, for example, is extremely uncommon. To the point that when I heard Alex/Dirk from Incubus use it on a track of theirs (Privilege IIRC), in 2001, on the radio I literally had to stop and figure out what band it was. When I realized it was Incubus and Alex (who I went to school with) I was relieved as only he, myself, Stanley Clarke and a handful of guys that have studied either Stanley or Les actually do that and I was worried about additional competition.
Again, it's an incredibly uncommon technique. I broke it out at a jam at the Baked Potato a week or two ago and a few guys ***'d on me. Stanley invented it in the 70s, but it is simply not mainstream.
Once you get past the "man that looks amazing" factor, and actually break down the parts a few patterns emerge:
1) Melodically Les can be a bit limited. Lots of flat seconds and minor thirds in his stuff. You do not get a lot of Primus songs in a major key. This isn't a problem, but it does limit their variety.
2) Since they're a trio, their tonal center is often somewhat ambiguous so he just tosses in a lot of chromatic stuff as well. It *works* because he doesn't clash with big chords coming off of Ler. In a larger band context he either has to hold back on that stuff, or pulls it out when other guys are laying *waaaay* back.
3) Unless you plan to write everything in your band, play bass, and sing, he's a bad example to follow too closely. I'm speaking from experience as someone that was the musically dominant force in a band that was nearly signed. His style is so very dominant musically, that I'd speculate if he had not developed as a singer or primary song writer for Primus, he probably would be a guy with a day job, playing kick ass bass in a cover band a few times a month for fun. He would have eventually clashed with the singer, guitarist, or producer otherwise.
4) Les uses three fingers in a galloping style strum, for triplets. Once you get that technique down a lot of his triplet work becomes really simple. e.g the solo on Those Damn Blue Collar Tweekers. If you use a traditional pick or two finger approach those licks take a lot of extra work to get down right. I picked up his three finger technique 14 years ago and fall back on that whenever I need to do quick triplets. It's just easier.
So...I'm still a big fan, and still go to shows, but after studying his techniques for as long as I have the "magic" factor is less present. You eventually start to realize there are guys playing bass, that you can barely hear, that are a bit more creative melodically, have a cleaner technique, and are maybe "better" bassists, but are clearly not being paid to be a "rock star".
From what I've read here, I'm not alone, as there are a lot of bassist on this forum that have enjoyed Primus for as long as I have, or longer, but have also studied Les to that extent.
So, lots of love from my end, but the worship factor has died off as I've grown up.
YMMV.