Ben;
Hi! The D's Flakpanzer 1A... I have not built this "premium" kit yet (it's in my pile), but did do the previous rendition, kit 6220. I did that as a "strict OOTB" and it was IMHO both a great and fun build and a rather stunning little styrene beast when all done.
The premium kit differs from the 6220 kit in only a few ways 
- one being that the 6220 kit came with a pre-formed brass PE front compartment plate, whereas the later kit has this in styrene. This could be a plus or a minus... the PE bit was a little fiddly to work with but, once done, really came out fine. Not having done the premium kit with its styrene piece, I cannot say what it looks like in comparison. I anticipate that it will maybe be easier to assemble the styrene bits on to, and I'll be thinning the edges of it, as it was made of pretty thin sheet metal.
The premium kit otherwise has much the same PE set as did 6220 - screens, gun shield bits, little chains, etc. with the "hi-points" being those bits used to make up the spent-shell basket... I think that I would go with scratching the netting with bridal-veil next go-round. The PE was both a pain and actually not very correct in scale nor appearance 
. The premium kit offers a different (and I think better version) trailer with the larger box which shows in most flakpanzer pics which have a trailer. (In the real world, most of these Flakpanzer 1A were accompanied into action by another special vehicle - an ammo-and-crew carrier "Laube" built on another Pz 1A hull - as the Flakpanzer had little room for the crew nor anywhere to store more then a couple of ammo cans. So that trailer may be more useful following a SdKfz 10/5...)
The other big changes from the 6220 kit lie in the improved road-wheels set and the inclusion of "magic tracks" over those links-on-sprues that the 6220 has. I personally think that the roadies are the best improvement offered by this new kit - they are new-tooled styrene wheels which are fitted with tiny brass (PE) rings to represent that essential (and lacking in Pz 1A and 1B kits before the D introduced these PE flange rings, and Tristar added in a styrene analog of the same feature on their last Pz 1A kit "early / late version" 35028) flange feature to really show the complex form of the Pz 1A/B road wheels . The new roadies are really cool, and the added rings make them sing and pop!
Otherwise, it's pretty much the same kit as 6220. The interior is the same - OK but can always stand lots of detailing and work. Strangely, the kits come with a radio set, but no antenna nor mount nor any other related bits... but the real thing may well have had a radio (albeit there is no place inside that hull for anyone to sit and operate it at!), so should also have an antenna...
The gun is, I think, the same for both kits - it's a good kit - taken right out of the Dragon Flak 38 kit box. But you don't get those PE main shields in either Flakpanzer kit (boo hoo ). The kit gun barrel, as discussed by others, is OK (and as I did mine OOTB, I used it - with some attempt to drill out the flash-hider a little to better capture its thin and rather delicate look) - but really wants to be replaced by a metal item if you want that better look. The RB barrels are great - I've used them on several Flak 38 versions. The flash-hiders (key feature) are grade A, and the length is pretty right on. One can easily improve the RB barrel (or any other which does not have that hand-grip knurled feature) by painting your barrel, masking it with tape bands, and spraying on 2 slightly lighter colored bands.
All in all, I think you'll enjoy it. I really liked the 6220 kit, and plan on doing the premium edition with some added detailing myself (hey, it IS pretty tiny as a panzer goes, so there's less problem fitting another one onto the shelf, as versus, say, adding another StuG or Tiger!
). Whenever you get building and posting, I'll be looking!
Cheers! Bob