It is. Each entry has its own distinctive charm. Obviously, the modern ones are more appealing to the eye, but all entries have their own forte. For me, FF8, FF9, FF10, and FF12 are the best gameplay-wise, the setting of FF8, a somewhat technofantasy is the best, but if you dig JRPGs, you'll find what you're looking for.

For example, FF7 has a great story, FF8 explores theories really intriuging, FF9 has the best playable character of all the series (Vivi), FF10 kicks you in the groins, but you still want more, FF12 has the battle system of previous entries refined, FF13 is beautiful and fast-paced, FF3 and FF4 have the old-school vibes with great mechanincs. I cannot praise this series enough. It's of its own. It IS Final Fantasy.