I haven't used the service since the takeover (I was out for the last day of Arriva service, though), but there are, perhaps, a few things that could be considered.
Go Ahead needed a large compliment of trained drivers on the first day. It's therefore not surprising that as former Arriva drivers used on the Fasttrack rota may have decided to stick with the routes and change employers that there was a shortage of drivers left. It is also known locally that a number of "management staff" (I want to say the Ops Manager) have moved from Arriva to Go-Ahead. Similarly, the decision not to bid was taken by the previous Arriva management, whereas the decision to extend the 480 back to Temple Hill (where it used to run before Fasttrack was introduced!) was most likely taken by the new management.
The road closure at Swanscombe has been something of a disaster for buses, especially as the rest of Swanscombe village is very narrow. There is no timeframe for reinstatement, which in any case would be some years away, given its precarious position on top of a chalk cliff, and it has been deleted from Open Streetmap entirely (see bustimes maps). One route was going to have to be diverted a longer way around to avoid an excess of buses in the Swanscombe area - I don't know how the decision was taken, but it seemed the 480 got the "local" whilst the B got the A2.
Unfortunately, that decision means that serving Ingress Park became difficult, with buses having to run past Bluewater to loop Ingress Park, then back to Bluewater. I have seen suggested elsewhere (maybe here, maybe on Facebook) that it might have been a better option to run some sort of Ingress Park shuttle to Bluewater or Darent Valley Hospital, so the B could continue through. The timetable has it at 14 minutes from St Clement's Lakes around Ingress Park to Bluewater, or 20 to Darent Valley. Adding an extra few for the leg between Bluewater and St Clement's Lakes and it could probably be done reasonably comfortably with 2-3 buses on a 15 minute frequency, to connect with the through B service at Bluewater. Those buses may well then be removable from the main service, meaning no overall increase in vehicles required.
I have more sympathy for criticisms of bus stop publicity - yes, there was a lot of set up being done on Saturday, but it wouldn't have hurt to have some sort of pre-launch presence. I saw someone putting up timetables in Dartford around 4pm on Saturday with a roll of sellotape: yes, there is a balance to be had between old and new, but at the same time, seems a little last minute (although in fairness, Arriva changed some timetables for Medway Council tendered services a whole week early - thankfully it was just a change of operator and not a change of times!).
Roger French responded to a particularly pointed critical comment stating he was well aware of the issues faced by operators and authorities, and that he was commenting strictly from a passenger perspective. In that sense, I didn't find anything that he wrote to be particularly "poor" - some of the vehicles are a noticeable downgrade from the Arriva fleet.
The bus station building remains, having previously been staffed by Bluewater staff and seems largely to have become a waiting room and toilet centre since the ceasing of printed publicity in the area in 2019. Given Go Ahead seems to join Transdev in still valuing an old fashioned "travel shop", however you refer to them as, Go-Ahead could definitely make a name for themselves by taking the lease, reopening it as a "Fasttrack hub" and generally making a deal out of it. (Do Ensign still print a book? Apparently Arriva have a leaflet for the 480, but nobody seems to have any). It could also be used as a promotional centre for the electric vehicles, driver changeover point, etc etc... ... ... (As always, anti-social behaviour in the toilets could be an issue, perhaps solved by having a "driver" and a "public" unisex facility, as you might find in a coffee shop, rather than traditional ladies and gents? It can't be easy for the drivers having to go inside the shopping centre to 'empty out' either).
Ultimately, we don't know what the intentions were in terms of publicity, either let down by others or which the funding was swallowed up in increased project costs, or what the real story is behind the late launch of the ieTrams, but I very much don't think it's a simple "Go-Ahead good, Arriva bad, KCC incompetent" or "Go Ahead Bad, Arriva Indifferent, KCC blameless" sort of affair as some are attempting to portray.