Yes exactly James, as Matthias mentioned above the BMPCC can only record at 24 and 30fps, you would need a higher frame rate (generally 60fps or higher) to produce smooth slow motion.
I recently co-directed and co-shot a short with a BMPCC, check the link below to get a sense of what the camera is capable of...
I have to echo some of Matthias' points regarding the image quality of these cameras (namely the ability to shoot in ProRes or Raw), which gives you a lot more options when colour correcting your footage in post. Also, the dynamic range on these cameras is pretty impressive as well -- very helpful if you are shooting in low light situations. A con would definitely be lack of slo-mo. Lack of 4K is possibly a concern, though not a deal breaker as most mobile devices (and this is a personal rather than scientific opinion) can't really distinguish between a good HD image and 4K, so it ultimately depends on where you plan on distributing your work. The batteries drain fast on these puppies as well but there are workarounds if you need to shoot continuously for 60+ minutes. Ultimately, it's what you do with your camera that counts, people are shooting with iPhones these days right?! So if cost is a real barrier then my advice would be to hone your craft with a "starter" camera. Good luck and happy filming!
For your consideration...
Police line-up supercut
Done! And thanks again for offering the opportunity to remix, looking forward to seeing how the community reimagines your short.
Remixed "Loot" into a music video. Check it out below.https://www.youtube.com/watch?v=lHWWI4o8zpw
Your short had "Miller's Crossing" written all over it...in a good way. :)