See I would score the gameplay about an 85 myself (if i were feeling generous) and the overall package as it was when I purchased on release a 65-68. So I agree with their scoring - sort of - but the article itself and their rationale is terrible. The broader mechanics have been changed significantly, the graphics and art resources have been fairly heavily reworked, and the heroes' class and leveling system is completely different. Add to that the lengthy and somewhat ambitiously crafted campaigns and I find the suggestion that this should have been an expansion bewildering at best. There are some things that do feel like they leave the game somewhat incomplete - what with wizards being mentioned as a somewhat important force in the world in cut-scenes but being strangely absent while dragons and elves are missing entirely. There is the feeling that some important creatures/forces from the lore as well as traditional presences in the game have been carved out of the world so as to provide easy fodder for DLC and an expansion to THIS installment.
Decisions about Conflux integration, reliability their online service during the time in which I took to beat the campaigns, campaign scripting bugs, and overall polish would cause me to rate the overall product at around a 65-68 at launch (and presently since the initial patch seems to have fixed very few of the actual bugs and design decision issues are not likely to change at all.) While the existing campaigns are quite long and meaty in their middle and end-parts, they are somewhat unnecessarily padded by tutorials which account for roughly the first 1/4 of each of them. Were the pacing of each of the campaigns accelerated in the first part by forgoing the mandatory tutorials for each and every race, the inclusion of a 6th faction with its own campaign would not seem excessive. So yeah with the technical issues, lack of polish in some areas, lack of a 6th faction including important staples to HoMM lore, and questionable design and policy decisions I would score the overall product similarly.
I don't think comparing this game to an expansion is very accurate way to criticize the game. Its problems are far more complicated - and potentially far more odious - than being an insufficient addition that would have served better as an expansion. It feels like an installment where they looked at the content that traditionally exists in a Heroes game then carved out 1/4 of it right on the drawing board and labled it "for future DLC." They then went through previously existing features (like starting bonuses and more than 10 starting heroes) and labled certain things as "extras requiring constant online connectivity." Its hard to say you don't get your money's worth though, considering the length of the campaign and comparing it to other full price titles currently out. It is fair to say that it doesn't feel like they delivered a whole Heroes game in some respects. The cynic would even suggest that many traditional components (a 6th faction, major species/races, starting bonuses, more than 10 heroes to use in quick-play) have been held hostage to justify Conflux as well as future DLC.