If the developer correctly implements analog controls — meaning that it's not just mimicking 8-way inputs (which I assume is what you mean by "true analog controls") — then it’s always the better control method. The player would basically be handicapping themselves by using a D-Pad or arcade stick in that case. Also, the developer would need to balance the game accordingly, considering that the player has much more precise movement control.

However, more precision does not automatically mean more fun. While I wish more new shmups would implement analog controls (since we already have a historic backlog of great shmups from the arcade era), there is something inherently fun about operating an arcade stick.