In my opinion, Warband's system was quite limited. There are optimal purchases that you should make, with the majority of gear being simply ignored. It is also possible to eliminate most of the drawbacks of any of the classes (inf, ranged, cav) by swapping gear with teammates (and please don't get me wrong, I love the teamwork and communication involved in gear swapping, I'm just not a fan that there are few, if any, downsides to it).
The class system presents you with a meaningful choice that you have to make with each spawn, taking into account your own team composition and that of the enemy. This choice can then be further tailored through perks.
Obviously, perks and classes still need some work, there is no doubt about that, but eventually, I think they will provide players with a fairer and ultimately better MP experience.
I feel that the only missing ingredient is the visual customisation that Warband offers, allowing players to inject their own personality into their character.