I can't say I want to get into a debate over whether or not the Bill in its current form should have passed. I did try reading the thing and couldn't tell at all whether it was an "unprecedented power grab" or just the action that may be required to make the changes as fast as will be needed.
But what bothers me is that Brexit is now a topic that, for the winners, seems to warrant no debate at all. No discussion over the procedure, no discussion over the final objectives, no discussion over the negotiating stance -- and not instantly adopting the government's position unconditionally is apparently comparable to the highest levels of treachery and treason. If it were just confined to AB then I wouldn't see a problem -- there are always people who seem to think that Democracy is about accepting that there's a winner, rather than accepting that the losers still have a job to do -- but that same attitude carries right to the top all of a sudden, May bitching about how time and time again the opposition were blocking her every move -- except (a) they weren't, as not a single piece of Brexit-related legislation was ever blocked, and (b) that's their literal job.
As I see it, the debate about whether or not we *will* be leaving the EU in a little under two years' time is over. We are. The debate over whether or not we *should* is not, and never will be. The debate over what leaving will mean, what deals and concessions both sides should make, and how Brexit is to be achieved, is also ongoing. Voting against this Bill is not therefore a slap in the face of democracy, but a vital part of it.