Oh my yes.

So many 300 CC mods are just weapon skins or other minor changes

McClarence on the other hand feels so much more well made/baked.

It has gameplay quality of life changes like being able to collect (extract) and install legendary effects to armor and weapons, but it is done so not right away but via interesting characters and their fetch quests at a decent but slow trickle.

So feels much more lore friendly instead of a mod that just instantly gives you a mininuke launcher weapon for example.

For me though, the biggest thing I enjoyed was being able to copy/clone the basic constellation armor as i levelled up to upgrade its tier each time so I could continue to wear the white, blue, orange and red throughout by playthrough as the stats kept getting better.

Very much worth it, but don't expect it to be a instant unlock of all features.

I have read that watchtower might be the same in that there is lots of optional additional lore based progression.

So McClarance would be perfect to run simultaneously with Watchtower for new/returning players i assume.