After reading some of the recent messages in the Xeno Xcalibur thread, it has come clear to me that there is one clear issue with Burst, and that is the parts being released.
The meta is currently filled with Stamina, Defense, and Stamina-Defense hybrids. While this is may seem to change later on, we already have some of the best Layers. What we have right now is a small, more compact, and round Layers. Neptune is an example of this which has both the stamina and the defense; something important in this metagame. This may seem fine, but that brings me to something NEET brought up: the wider the (diameter of the) Layers, the easier it is to Burst. Dual Layers are currently being released, and are usually wider than their counterparts, meaning that (theoretically) they will mostly likely be easier to Burst.
This could mean that DeathScyther, Neptune and Wyvern would be top tier for much longer, as we have already seen what they did to Wild Wyvern, and K2 still being outclassed by Neptune and Wyvern (even though the size is pretty much on point with the original). Neptune itself is on par with Wyvern for Defense, and has better Stamina, which really makes it the better option considering it's versatility. And considering what was said above, I would find it hard to make a better Defense (and Stamina) layer than Neptune.
But one of the bigger, continual problems is the lack of a good attack Layer. So far, the best attack Layer in the game, Valkryie, is disposable after 20 rounds. The only good substitutes to Valkryie would be Xcalibur and maybe Minoboros so far, with V2 and D2 both being bad. It seems that the Layers will either have bad attack points (which is the case for both V2 and D2), or be too wide and be easier to self-Burst (which has not happened yet, luckily). Along with that, if we do manage to get an Attack with good contact points, there is also the diameter of the Layer which would allow for it to Burst easier.
Let's keep hoping new Layers will be better, since it seems that the only good parts we are getting are just Disks and Drivers.