No horrible bugs yet for me, except for the game locking up in the middle of one long quest and had to force reset. It actually saved part of the progress which was nice.
The maps do seem a bit more tedious than previous maps. Some story quests are certainly tedious as well, but I don't think this is anything new with Borderlands games.
Took me a while to accept the O2/jumping slam stuff, but I'm fine with it now. I managed to get a decent, very low level O2 back that gives health on O2 canister pickup, and this thing has been great. They drop so often form enemies that I never find myself thinking about O2 level. I actually ignore all of the O2 nodes, because turning them on eliminates my ability to pick up the canisters, and thus heal.
Only complaint right now is that it really seems like BL2 with new maps. Badass ranks exact same, and much of the loot is the exact same. Many of the same legendaries and gun types, just ported over.
And the completely broken Moxxi heal pistol (think Grognozzle from BL2/Tiny Tina) occurs WAY too early in this one. If you want to never die--just keep the Moxxi Probe in your inventory and never turn in that quest. I think you get it as soon as you arrive at Concordia and talk to the female version of Scooter.