The bottom line:
Both kits are certainly buildable, and make nice representations of Ju 88s when finished. I would not hesitate to build either again, and plan to do additional variants of each. The clear parts are a bit fiddly on both, most likely this is due to limitations of the molding process in capturing the many bulges and curves. Canopy masks are a big help. There are several other aftermarket parts for Ju 88s already on the market, so lots of additional detail can be added for those who want to do so.
The main strength of the Hasegawa mold is the number of variations issued – the last time I counted, there were eight different boxings in their catalog, and many of those provide Jumo and BMW engines in the same box for multiple types. Given Hasegawa’s history, we can likely expect more variants for years to come. Even though it is a solid kit, there are some inaccuracies which most modelers will want to correct, such as the gear placement within the nacelles, opening the gaps in the nacelle faces, and removing the cockpit floor. We will just have to live with the bend in the wing between the fuselage and the nacelles, but from most viewing angles this is not noticeable. The kit also has its share of technical issues – fit problems with the engine nacelles, ventral gondola, and small nose windows, plus several ejector pin marks in bad locations are examples. Fixable yes, but also avoidable. The Hasegawa kit was more work to build, I felt I was playing catch-up to the Revell throughout construction.
Revell has issued a nice kit at a nice price. It is definitely more refined than some of their earlier kits which I have built (Ju 290, He 177, Ho 229 to name a few). Parts are finely detailed, thinly molded, and free of flash and ejector pin marks. Fit is excellent. Engineering is well thought out, an example of this is the separate upper fuselage piece which allows the filler cap detail to be captured, and which fit beautifully. There are a few nagging bits which bothered me enough to correct, such as the spinners, guns, bomb fins, antennas, and (upon reflection) the main gear legs. No insurmountable issues, and no sub-assembly which was fraught with errors. A good solid kit, and a great value at the price. This is the better of the A-4s. Revel has issued a C variant which is unfortunately now hard to come by, and has announced an A-1 version.
Completed pictures here: https://inchhighguy.wordpress.com/2020/01/02/revell-of-germany-ju-88a-4-in-1-72-scale/