Not that I can add anything dramatically new about this one but here's my experience with the exam:
Firstly I have no Cisco hands on experience...yes laugh all ye who already get to play with the actual boxes as I'm busting my ass trying to break into Network engineering

(I have 10 years Desktop/Server support, just no backbone exp). The prejudice against knowledge vs. experience in Cisco environments is pretty amazing - dont get me wrong I value experience over a cert. myself but knowledge in itself shouldn't be almost weightless. Anyway, sorry getting off track. I mentioned the no-hands on as there are no sims for the CCSP (That I could find) and I am writing this account from the point of view of someone who had to memorise the commands only and that may be of value to others in a similar position.
I'd rate the exam as about 7.5 or so in difficulty. I had a job interview coming up and hurried my study to try and pass this one beforehand for some extra resume-firepower, hit the books for a week and was pretty damn surprised when 'Congratulations' popped up onscreen. I used the Cisco Press dedicated 642-502 study guide and their CCSP Flash Cards and Quick Reference guide. The only sim I had access to was my old Boson CCNA sim. I see that their CCNP sim has some components that might be useful (AAA, IPSEC etc.) but couldn't afford it at the moment. Sooooo really I just redid the CCNA labs to refresh my basic CLI knowledge - which did actually make memorising the SNRS specific commands easier (I guess it helps get you into a CLI state of mind....if that makes sense

). On my first few runs through the books I skimmed the Show and Debug sections focusing mainly on the execution commands,
I advise you don't. They are an integral part of the course and thankfully I realised that before sitting the exam. Besides the exam factor it just makes sense that a large part of keeping a system secure via the IOS firewall suite is being able to monitor it.
I had 3 sims, not going into specific details but they covered a wide spectrum of topics and involved multiple tasks from different areas to complete - all in all I think the sims accurately tested the course material. The output of various show and debug commands also played a large part (as I mentioned earlier), so know your main monitoring commands and how to read the outputs for specific data as quickly as possible.
If you have recently completed your CCNA then this isn't too hard an exam overall, it's really a security extension to it (Since you are dealing with the same basic Hardware platforms in Switches and Routers). Besides the exam/cert. I found the course very interesting. The 2 books (The main guide and Flash cards) complemented each other quite well. Both are very concise and while the SNRS main guide is just one book it has, im my oppinion, as much information crammed in there as the 2 CCNA books (Sorry, my only frame of reference at this point). While the amount of information presented can be intense they are both laid out extremely well and trying to find say the source paragraph for the generic versions of specific commands you are interpreting later in the book is quick and intuitive. I came out of the exam knowing that what I did miss was purely down to me and not something that was left out of the books, so I highly recommend these 2 guides.
Anyway that's it. I hope someone out there might find this useful.