It does not matter if Boris Johnson can be trusted or not and it does not matter if his "deal" delivers anything new, what does matter is that he "appears" to have proved that he can be trusted to deliver. This makes it even more likely that he will win the next election with a landslide majority (and it was pretty certain that he would do so even before he "successfully" negotiated a deal with the E.U.). He is now in the perfect position to fight and win a general election and the remainers in Parliament along with the D.U.P. are going to hand him the opportunity to do just that by throwing out the deal this Saturday.
Since before he became prime minister the opposition has been playing into Johnson's hands whilst displaying less political acumen than you would expect off a tantrum-throwing toddler trying to get its own way.