Lumia 800 is pretty old at this time and gives no WP8 support. If you choose to stick with a Lumia device, choose those with *20 suffix (720, 920, 1020 and also 925, 928) as they are WP 8.0 ready and would be upgraded to 8.1 soon. I'm using a 920 for year. WP8 is kinda good at the moment. I am happy to see it being fixed time by time (can you believe you are given ability to manually close an application just 1 week ago?). Wait a few more weeks for Lumia Icon and see if you love it.

It's difficult (to get used to W8) at first, but with some searches you will be there, perform any tasks you want in a new way. I used W8 from the beginning and going to love it until the end (if any).

Speed

• Simplicity
• Multiuser, multi-project
• Drag and drop stuff / minimum clicks. Be as fast to modify as Notepad or Excel
• Track priorities, status, assignees, due dates, milestones
• Roll up of values (eg add all the time estimates for child items and show it on the parent)
• Email alerts
• free form comments within each item
• uploads of screenshots or docs

I've used Fogbugz[^] on my previous project. It's not free but it meets almost what you want.