I trialed the T-slim this week, as I am also available to upgrade my current pump ( I use MiniMed) There were a lot of great things about the T-slim: The size, ease of use- I loved having pretty much evertything I wanted to see on one screen, and the IOB feature was awesome! I also loved the battery life, and the fact that you plug it in for 5-10 minutes and your battery is full :)
The drawbacks for me:
the bolus history is confusing ( It shows the same bolus multiple times, and it only gives you a history of boluses that day)
You fill a black cartridge of insulin, and you can't see how much insulin is in there, or if there are bubbles.
It takes forever to change your pump site, because of all of the steps you have to go through to load the cartridge
It does not show you the insulin being delivered, it just beeps or vibrates once delivery is done
I had to increase my basal rates by 15%
And finally: the luerlock that connects the tubing to the cartridge.. this twisted off without me noticing 3 times in two days! I haven't heard of it happening with anyone else, but it was a dealbreaker for me. In the end, I decided to snick with Medtronic :)