In just a few hours, Microsoft will unveil the biggest Windows Phone update since the platform launched in 2010. Windows Phone 7.5 “Mango” added more than 500 features, but Windows Phone 8 “Apollo” should be even better. A few features have leaked out here and there, but when compared to Mango, the Apollo rumor mill has been almost silent ever since an internal video of Windows Phone Corporate Vice President Joe Belfiore was leaked back in February. So while we know about a few improvements on the developer side, we know almost nothing about the consumer-centric features and changes to the UI.

Windows Phone 7.5 is a great platform, but it isn’t perfect. I could come up with a long list of things I’d like to see added to the OS, but a few, in particular, stand out to me:

Sync app data between devices

Windows Phone and Windows 8 “light up” as soon as you sign in with your Microsoft account, automatically pulling in your emails, contacts, calendar, and much more. Unfortunately, the same cannot be said for apps. App data is siloed on the phone, and it’s impossible to back this data up without app developers adding this capability on their own. Windows 8 can sync app data between devices, and Windows Phone 8 should too. This would make it much easier to swap between devices or move your data over after a replacement or upgrade.

Improved app restoration process

Speaking of replacing or upgrading a device, the process of re-downloading all of your apps is a painful one. The Windows Store on Windows 8 has an elegant solution to this problem, and I’d like to see it make its way to Windows Phone 8 as well.

Sync data with Windows 8

If we’re already syncing app data between Windows Phone devices, why not extend the sync capabilities to Windows 8 as well? Windows 8 will allow you to sync a wide range of settings and personalization options between devices, including browser history, favorites, and passwords for apps, websites, and networks. Syncing this data with Windows Phone 8 would give users a seamless experience between devices and operating systems, as well as make favorites on the phone usable. At this point, I rarely use favorites on Windows Phone because there’s absolutely no way to back up or save them anywhere else.

Deeper SkyDrive integration

Windows Phone already includes SkyDrive integration, but I’d like to see Windows Phone 8 expand upon this even further. For example, it would be great if you could save a file (not just an Office document) directly to SkyDrive or stream your music collection as if it were stored locally. SkyDrive now allows you to pay for additional storage in addition to your allocation of free space, so why not let us take complete advantage of it on Windows Phone?

Expandable memory

As great as the cloud is, it doesn’t work in all circumstances. Accessing SkyDrive without an internet connection is problematic, and streaming music often sucks up battery life and data. As a result, expandable memory is crucial. The first generation Samsung Focus unofficially supported microSD cards, allowing me to store my entire music collection on my Windows Phone. It was, in a sense, a souped-up “Zune HD 2” with phone capabilities. Unfortunately, I had to give that up when I purchased by Nokia Lumia 900, which only has 16GB of internal memory. In my opinion, expandable memory is a must.

Let apps integrate deeper with the OS

Windows Phone already lets apps integrate with the OS in many respects, placing shortcuts to apps in Hubs, adding options for quickly sharing photos and videos, etc. Apps cannot, however, do things like place additional information in a contact’s profile. Apps should be able to integrate seamlessly into the OS, allowing you to place and receive Skype calls as if it were a regular phone call, for example.

What’s the future of the Music + Video Hub?

At E3 2012, Microsoft announced that Zune will soon become Xbox Music and Xbox Video. What will happen to the Music + Video Hub? Will it stay as it currently is, allowing you to sync your local collection to the phone? Or will that be the domain of the Xbox Music and Video apps? What will happen to the Music + Video Hub’s podcast support? The announcement of Microsoft’s next generation media service raises a lot of questions, and we probably won’t get answers at the summit. It is, however, something we need to know.

This is by no means an exhaustive list; I could go on and on about other features I’d like to see in Windows Phone 8. In fact, many of these features are already rumored to be in the OS. Our sister site, Anythingbutiphone, has a great list of all the confirmed, rumored, and debunked features in the update. Thankfully, all (I hope) will be revealed at 9:00 a.m. Pacific tomorrow morning during the Windows Phone Summit. I’ll be covering the event live from San Francisco, so stay tuned to Pocketables for the latest information about Windows Phone 8.