@NitromethaneAP Similar story with me, started with Bangalore as my 1st choice but have been using Pathfinder as my 1st choice lately and it's a whole new ballgame (still like playing as Bangalore though).
It's a way more 3 dimensional game with PF than with any other Legend. Sure, any Legend can get high ground by climbing, using existing zip lines, and jump towers but PF can gain high ground everywhere on the map and way more quickly. Huge mobility advantage, coupled with finding that last ring location for positioning makes him a great Legend and fun to play.
In addition, the mobility helps you get to loot locations quicker so you can get the best loot and your loadout first. When using the grapple to retreat PF is harder to hit, typically, too.
But, aside from his ability to grapple enemies to himself, he has no ability to inflict extra damage, nor heal up faster, nor conceal/cloak himself. So to me he isn't too overpowered in any way.
Like @Anlbrd mentioned, his mobility is his one and only deal. And that can very much be a double edged sword, esp since grappling and grappling well is another tough to learn skill. Even if you grapple as intended it may remove you from a bad situation and into a worse one.
Most mobile? Yeah that's PF's MO. OP? Nope.