I play this every day and find it the best of the solitaire games in Win8. However, you said you'd love to hear from me so here goes:
I play this as a 5-10 minute distraction thru-out the day so it is very frustrating to have to wait for the animations before you can start a game. This is particularly annoying when doing the daily challenges. It seems to take ages to log in (Why can't this be a background service, leaving you logged in all the time whilst your PC is connected?), then there's a wait for the challenges to load, then you have to wait after clicking 'Play' on a challenge for the banner animations to slowly swipe off the screen before you can play. I know this is to make it look pretty but once the game has loaded, we really don't need it to be so slow.
The 'Undo' button is not very responsive. I can click furiously with my mouse and it only reacts when it wants to - again because it has to wait for all the animations (This is not necessary when undo-ing an action surely?)
Performance is very 'laggy' on some card animations, with noticeable judder. My PC is a 3.4Ghz Core i5 with 8Gb RAM, a Samsung SSD and an AMD 5870 graphics card so way more powerful than this game needs.
All the above points also apply to Minesweeper.
Finally, the premium price. £6.99 a year is very steep, why not make it a one off fee?