I am on the same boat...WP7 looks very promising but missing a few key features that would eventually come in Mango/updates.
There are a few things keeping it from a perfect Android replacement and maybe you or someone can help clarify.
Navigation - Need turn-by-turn app. After coming from Android, it seems like a standard on newer phones.
Google integration - Need good gmail, talk, calander, contacts, etc replacement. How good does the Live tiles work with Google/Exchange?
Mac OS - Does WP7 hardware work flawlessly with Macs?
RSS integration - How does RSS feeds work? App or built-in to OS?
Password App - Good replacement for SplashID?
Words with Friends - need good games but this one most due to addiction.
That's it for now and I hope this side of the fence works as good as the Android/iOS sides.
ok, I'm new to wp7, but I'll answer your post with what i know so far:
Navigation - Need turn-by-turn app. After coming from Android, it seems like a standard on newer phones: Bing Maps is nice. Hit the Maps App > Enter your destination address, and within seconds step by step directions appear on the screen. There is also an app called: "Turn by Turn Navigation" that offers voice-guided driving direction. Btw, you can "try" any app/game in the marketplace before you buy. Love this feature. You basically get access to the complete app minus a few features typically which is nice before you commit.
Google integration - Need good gmail, talk, calander, contacts, etc replacement. How good does the Live tiles work with Google/Exchange?: I use Gmail, Hotmail, and Yahoo and let me tell you the mail clients are better imo than the Android Gmail client. Very clean interface and when a new email comes in, your Live tile will display a number letting you know you have a new message. I dont use Exchange on my device, but I've heard it's very good and better than exchange on Android.
Mac OS - Does WP7 hardware work flawlessly with Macs?: Zune Software right now is only available on PC, but they have a nice app for MAC called: Windows Phone 7 Connector for Mac. I use a Mac as well, and this software is top notch:
Windows Phone 7 Connector for Mac | Windows Phone 7
RSS integration - How does RSS feeds work? App or built-in to OS?: There are a zillion RSS feed apps, it's not currently built into the OS, but there is an app called "weave" that is killer. It's super smooth and works like no other RSS app on iOS or Android:
YouTube - WP7 App Review: Weave (WMPowerUser.com)
Password App - Good replacement for SplashID?: Not familiar with SplashID, but I have seen password apps in the marketplace.
Words with Friends - need good games but this one most due to addiction: No words with friends yet, but games on wp7 are killer and look awesome on the trophy: Bejeweled Live, Doodle Jump, Fruit Ninja, de Blob, Full House Poker, Hydro Thunder, Pac-Man CE DX, Parachute Panic to name a few. Btw, you can also earn achievements for these games and if your an Xbox gamer you'll love this integration.