How bad is Mindows Media Player, really?

[msh441]

I'm getting my first WinMo phone with a convienient 3.5mm jack (Touch Pro 2)... so the question of mp3's has now come up.

I've been using iTunes for years now. None of the files are purchased/restricted, but many have been burned from CD in AAC(mp4) format. I'm curious if these will play in Windows Media Player. If so, do I have to do anything extra (codec or other extra)?

I've seen options for converting to standard mp3... but if you saw the size of my music collection, you'd see why that's a daunting task.

I've briefly looked (read: glanced & know they're there + popular) at programs like Kinoma Play and others... but I'm just curious what they will do that Windows Media Player won't.

So to sum up:

So what's the best WinMo player that will do AAC/mp4 out of the box?

Why is it better than what'll come with my phone later today?