It's not without promise, but it just falls completely flat. Everything about it does so. Some of the reality of that decision to cancel seeped into the writing and in front of the camera. There's none of the optimistic spirit found in Terra Prime, and almost all of Season 4. It has been broken by the realisation, this is it... there's no "one door closes, another one opens" sentiment to fall back on. They even kill a popular character to hammer home exactly how bad we should all be feeling.
Making the finale somekind of "baton passing back to TNG" exercise pretty much ruined it for me. Having Arik Soong (who was at least a boné fide and unusual ENT character) was about as much of a nod as fans needed in that direction frankly. I'm sure if you'd worked within the Trek factory back in 2005, TNG were definitely the glory days of high ratings and massive media interest. But a lot had changed since then and bringing those guys back was demeaning to a show which had built up its own (obviously fewer in numbers) following. Coming off the poor reception of Nemesis, which did nothing to elevate TNG's fortunes, it made even less sense. It was a bit like getting Kurt Russell and James Spader to lord it over an episode of Stargate SG1 or Atlantis...
I wanted some parting connection to TOS, while keeping ENT the centre of attention. Something like the Generations opening, but in reverse. T'Pol with old man Archer in a wheelchair touring the NCC-1701 or the like, giving his blessing and passing away. I'd have thought that link to the original and next show in the timeline, would've been an obvious and fitting end myself.
We didn't quite get full circle, just thrown back in time to TNG... and left to hitch a ride back to the beginning!