As far as I know, attorney Hussain Hamdan isn't counsel on any of the lawsuits that have been filed against Chapter 35, but he's provided some excellent pro bono work for those challenging the new law's myriad infringements on the right to keep and bear arms. 

Hamdan points out that Massachusetts gun owners are already subject to some of the most restrictive laws in the country, but they "aren't the ones committing gun crimes." He rightfully argues that the new restrictions have only made it more difficult (and, I'd argue, downright dangerous) to exercise our Second Aemndment rights, while violent criminals aren't likely to be deterred because of the new restrictions. 

Though Hamdan is right, he's not exactly breaking new ground with those arguments. But his column also raises several points that I haven't heard many people talking about. 

Those with Firearms Identification Cards (FIDs) — the lowest level license and the only one available to those under age 21 — now face legal trouble for owning semiautomatic firearms. FIDs previously authorized ownership of low-capacity semiautos, for example the M1 Garand. These now require a higher level License to Carry (LTC). The statute’s language potentially “grandfathers” continued possession of anything a person’s license permitted when it was last issued or renewed; but if your FID is about to expire, you presumably must upgrade to an LTC, (with the new, as yet nonexistent, training requirements), or surrender these guns.

There is apparently no compensation, (constitutionally mandated under the Fifth Amendment), for lawfully acquired property thereby confiscated.

The state would argue that they're not "confiscating" firearms. Existing gun owners can always keep ahold of them... so long as they don't mind being prosecuted and punished for doing so. 

Hamdan also finds fault with the state's expanded bans on "assault weapons" and "large capacity" magazines. 

Most semiautomatic rifles are now “assault-style firearms” (formerly “assault weapons”), because forward hand guards meant to prevent burns are now an assault “feature.” The authors of such provisions are clearly either unfamiliar with guns or unconcerned for the safety of gun users. As if this weren’t enough, unelected bureaucrats now wield unlimited discretion to define anything not already specifically banned as an assault weapon if they feel it should be. 

The law contains convoluted language about high-capacity magazines, (you can own pre-1994 ones, but apparently cannot carry, load, or transfer them in-state except to a dealer or via inheritance), 3D printers, and computerized milling equipment. Overzealous officials may persecute folks carrying older guns that these magazines feed, as well as 3D printer and milling equipment suppliers who aren’t even manufacturing firearms.

I encourage you to read Hamdan's entire column, which also delves into the unfunded mandates, unwritten training curriculum, and unabashed defiance of the Bruen decision by Massachusetts lawmakers, as well as the "procedural atrocity" that led to the law's language and passage. Hamdan's arguments may not win over the most ardent anti-gunners in the state, but he does an excellent job of laying out the legal and practical problems with the law billed by the Gun Owners Action League as the "Lawful Citizens Imprisonment Act".