I've noted that the switch on the clutch that's supposed to prevent you from cranking the engine with the clutch engaged doesn't alway require that the clutch be completely disengaged, so it will crank a bit slower. It's possible that there's air in the hydraulic clutch so that even when you do push the clutch pedal to the floor it's not fully disengaging. That's pretty likely if you had any leakage while replacing the clutch.

It's also possible that the new clutch is binding on the splined shaft of the transmission instead of sliding on it. It doesn't take much of a kink or burr on the shaft to hang up the friction plate. Hopefully a dab of grease went on the shaft before assembly. And of course it's possible the friction plate went on backwards. A lot of the aftermarket stuff isn't marked and the extra length on the neck of the splined insert (that's supposed to face the transmission) in the clutch plate might contact the end of the crankshaft and keep the friction plate in contact with the pressure plate. I say might 'cause I've never actually done it, but there must be a reason there's a inner and outer side.

I'd go with my first guess. There's air in the hydro side of the clutch so it's not fully disengaging. It would only be really noticible in first and reverse or starting. The rest of the gears the syncro rings would accomodate.