Just purchased a new LG Optimus 2X smart phone (our first) from Wind and ported our service from Rogers. We were in and out of the McLeod Trail store in about an hour (would have been shorter, but we asked a lot of questions). We spoke with a very knowledgeable young man who answered all our questions and more. He didn't push one phone over another and asked us about our requirements. In the end, we chose the LG over the Nexus S and signed up for Wind's Smart Voice Plan ($25) with unlimited everything in your home zone and a data add-on (unlimited for $10).
The number was ported over night. After the port, we ran into our first problem in that the data option was not working. So, I phoned Wind's CSR who gave me step by step instructions to remove the battery, SIM card, and reboot procedure. Didn't work, so I called back a second time. The CSR created a problem ticket and immediately put me on to the second level Tech support. Both were very helpful and understanding that I was a smartphone neophyte. The Tech got me up and running in no time.
Haven't really had the chance to use the phone much so far, but the calls I've made so far are quite clear. Surfing the internet or using other data has been very quick in my area (Lake Bonavista).
Why did we switch? Value. I've checked out a number of other providers including Rogers (they are not competing right now) and determined that despite the fact that Wind is a start up, they were the best option for us.
I'll post again should my initial thoughts are proven incorrect.