Thunder Blade is a hybrid blaster that alternates between vertically scrolling fare and "into-the-screen" sequences. Both of its play modes are afflicted with the same disastrous flaw: they're choppy as hell. Honestly, I'm not one to allow visual elements to make or break a deal, but the jerkiness here is revolting, and it impacts the gameplay significantly. Hit detection is way off during overhead play (which actually often works in the player's favor) while it can be hard to judge the positions of environmental hazards during the behind-the-'copter scenes (which, of course, is not beneficial to the player at all).
As hard as I am on it, Thunder Blade is not terrible. It's, uh, functional, I suppose. But I see little reason for anyone to go ahead and purchase it, as neither of its play modes stands up well. Space Harrier and After Burner II are faster and more challenging than the forward-flight levels here, not to mention that they feature smoother visuals and better tunes (though TB's music actually isn't bad). And we don't even need to look to CD to find about a billion PCE verts that crush TB's traditional blaster segments.
The choppiness in the vertical levels is completely unjustifiable. The bland, ugly terrain; small, simple sprites (the same few of which appear over and over again); and wimpy weapons don't comprise an adequate explanation. We're not talking ambitious stuff here.
I'm not letting these parts off the hook either, as Space Harrier, After Burner II, and even Jimmu Denshou show that stages of this style can be pulled off pretty well on the system.
Most of the bosses are large machines that require you to weave amid periodic blasts and annihilate cannons.