The biggest gains i'm seeing from 3.6 is Bowser's tech chasing capability. Once you get a knock down or your opponent is 'staggered', it's definitely easier to bully people offstage now that initial dash speed is better, nair still having good armor, and KK being more reliable. Considering his ledge game is still high tier, I think his new design is suppose to cater to get edgeguard kills more often. It's probably why fsmash is faster but not as strong. It's likely that you'll get your opponent offstage after landing one yet it still retains high damage/shield damage.
Emphasis on 'suppose'. Like many have already mentioned, the lack of compensation for the nerfs Bowser has received still makes his job really hard to do. The fact is that a lot of his moves are still not good in neutral and armor reduction (good idea though) leaves him more susceptible to losing in neutral. I can see the longer-ranged Flame Breath (hooray) being a partial compensation for the dash attack nerf, but the start up angle on Flames cannot be manipulated (that would be nice to have even if duration is reduced again) and is still slow to maneuver up and down.
I would've liked to see some good work done on his jab by making it frame 5 or even 4 instead of 6 (technically it is Frame 5, but the hitbox starts in such an awkward position for anything substantial to come from it) and having it link into jab2 or tilts more reliably. This would be a great way to use a launcher other than than dash attack. Jab1 still has great range and decent damage at 6%, but the relatively high rate of escape prevents it from being a solid move outside of jab resets, I think. Either that or start the IASA frames a tad bit sooner, perhaps with a slight reduction in damage and a different angle. Bowser would be able to do more things out of jab, allows for better CC'd jab chains, and there's still counter play as the opponent can SDI the jabs and prepare for Bowser's follow-up.
Anyone have an idea on how useful dtilt2 is? The only real use I see is pushing away a shielding opponent. Dtilt 1 doesn't link into dtilt2, and its edgeguarding application is tedious and redundant when we already have dtilt1 among many other better options.
If Bowser had dtilt2 removed along with reworked dtilt1 frames/properties to better work with an improved Jab1, he would actually have a good degree of shield pressure/close quarter combat options. Throw in the Flame Breath angling buffs and 3.6 Bowser could've been dope.