It is a quite impressive galaxy even with a smaller aperture.
My notes from an 203mm scope in 1995:
"large, roundish-oval, face-on spiral, outer areas diffuse like M51, very impressive!!!, bright stellar core, mottling in arms regions, irregular edge outline, best magnification 145x"
My first view of this was in 1963 with a 108mm reflector, so it is visible in quite small apertures.
It really comes alive around 200x in my 318mm reflector. It is up there with M51 and M101 and M74 as Dragan suggested.
I was looking at nearby NGC4312 in May (very nice nearly edge-on in same low power field as M100) when I moved over to M100 and almost needed sunglasses. It is really bright for a face-on spiral.
A great OOTW.