That's actually a fairly nice Dob, with good optics, a nicer long focal ratio, a crayford focuser and various other little refinements. I'd be strongly tempted by the adjustable brake since that will at least partly address one of the weakness of the Dob format. The fact it is mounted on tube rings is another plus since it means you can put the scope on another mount if you want. In terms of upgrades there isn't really much else worth doing since the focuser and finder (the two common upgrades) are both good already.
However, it also strikes me at very expensive for what it is. For £40 more I can put a similar spec (albeit slightly less refined) Sky-Watcher tube on an EQ3 equatorial mount with goto. Or for less money I can get a manual (but computer upgradable) EQ5 that will take both this scope or a much bigger one. Or if you want to stay with a Dob I see 10" Dobs going for £400.
In summary, yes it's a nice scope but it does seem expensive.
