They are not by any stretch of the imagination a top tier brand. They will do fine for most casual shooters but I would not take one to a class.
Honestly though, for the money I feel you can do a lot better.
Ditto, MOR all the way, including but not limited to the following short-cutting(cost-cutting not reflected in the price) measures,
1. BCG are not properly staked(gas key)or MP tested, rather batch tested. Improper staking leads to short stroking which means your weapon is useless, BCG's have been known to shear or fracture during heavy use!
2. Barrels are not mil-spec 1:7 but rather 1:9 which effectively eliminates the reliable shooting of bullets in excess of 69 grs in weight!
3. No M4 Feed ramps, leading to unreliability with hollow or softpoint ammunition!
4. Trigger guard fabricated from cheap plastic, so cheap that they routinely break when opened up to accomadate a gloved hand!
5. Improperly indexed barrels almost a common defect from the factory, trust me, this is a real PIA!
6. Fit & finish amongst the worst in the industry, every Bushmaster I've ever handled has had the finish already flaking and chipping long before even leaving the shop!
Now perhaps the Carbon version is a spectacular representation, perhaps it's not, but the XM15 E2S carbines I've owned and looked at over the last 8 yrs or so were universally chincy, though if you swap out the BCG for a DD BCG you will have gone a long ways towards fixing them, improperly indexed barrels are discovered when trying to attain zero and you find that you must adjust windage all the way to the left or right, trust me on this, it's a common factory defect from Bushy.