Nah X7 in my opinion is much better than x6. Have you ever played X6? It's a friggin nightmare. It's hard for all the wrong reasons. X3 was harder than X6 but in a way that felt fair and was still fun. X6 always feels unfair and it's more irritating than fun. I only play it to get through the series. X7 is not a masterpiece, but it's much better.
The only thing I dislike about X4 is the voice acting, especially for Mega Man. I always play it as Zero.