Recs.
Updated
Specs
Pros
Pro Run concurrent tests in parallel
Open source project accounts are limited to at most two concurrent VMs.
Pro Might be able to test on real iOS devices
It's not very clear if real iOS devices are available for automated testing.
On one hand, https://www.browserstack.com/mobile-browser-emulator is all about emulators for both Android and iOS.
On the other, https://www.browserstack.com/automate says
"Test across real iOS devices and Android mobile emulators"
Then again, https://www.browserstack.com/list-of-browsers-and-platforms?product=automate lists "real iOS devices".
Cons
Con Immature approach to cyber security
Surprisingly underprepared for answering basic questions about cyber security during the evaluation process. Replies to the questions may take days to get, and they only include questions for the prospective client. As though, for instance, the answer to whether or not the client had budgeted for testing would influence their answer to the client's question, "Do you support two-factor authentication for your users?" This is discouraging, but their tools are very nice.
Con Real Apple devices are unreliable as of August 2015
Real Apple devices are a new feature that BrowserStack has introduced. At the moment (August 2015) there are unreliable. Excerpt from an email reply from BrowserStack support:
we provide real iOS devices (Beta) and iOS simulators for Selenium browser testing on Automate. Since these devices are in beta, you might encounter a few problems while running tests on them.
To avoid this issue, we would suggest you try running your tests on iOS simulators.