I think the opinion I hear echoed on this website in particular is that he types too many people as betas through his own typing service. There are explanations as to why this is, and while I understand the skepticism and think it's valid, it doesn't mean that his typing service is bunk or a scam (or at least that it intends to be, which is something I hear on this forum sometimes).
I'm not gonna go out and deny that many of the people he typed as betas (Penny, Vex, North, Peteronfiree, Shotgun, Viktor...)* already were usually considered staples of that quadra on this forum. Others such as myself, Aster, Ash, TGF, Duschia who either doubt their typing or have others doubt the typing (or both) are considered less "obvious" examples of beta. And I haven't heard complaints of those who he typed as something non-beta.
The point is that it's likely Gulenko's typings have a beta slant, though personally I always thought betas were the most common and deltas rare, with gammas and alphas being fairly common too.
Other than the beta thing, Gulenko's ideas are fairly new and may appear strange to some people. This is typical when someone has an unconventional idea in a field with well-established prejudices (for example the idea that types are evenly represented among the general population).
*Shotgun wasn't considered beta before