I've just come back from a 7 day Exchange 2003 bootcamp, doing both the 284 (implementation) and 285 (design) exams. It was pretty tough but then I only had Exchange 5.5 experience before the course and 2003 is obviously radically different.
The new format MS course books are very good and we also got a copy of the Exchange Server 2003 Administrator's Companion MS Press book which is very good (we got an examcram book to but I didn't use it).
I think the standard 5 day course for just 284 could be pretty boring as you'll likely have to do all the labs and sit through all the videos, on the bootcamp we only did the more involved labs (and in our own time) and watched 2 of the videos. The other thing is at the bootcamp you get 2 physical servers and told to build them pretty much how you want (e.g. you could have 2 back-end servers or a front-end/back-end configuration), rather than getting supplied to pre-configured Virtual Server images you get on most courses.
The exams themselves were pretty rough, 284 was 30 questions and it was question 14 by the time I was 100% sure with my answer

I had some stuff that weren't really Exchange at all so you need a good general AD (inc. GPO, IPSEC, Certificate Authorities etc.) knowledge.
285 was an example of MS exams at their worst IMO. They've changed the format of the design exams from a lot of waffle in the scenario to much more concise information, but there's still a lot of it - the result being there's far far more technical stuff in each scenario than either the AD or Security design exams I've previously done.
You only get a set amount of time per scenario to, by the time I'd read through the scenario and written down key stuff/drawn the topology I had under 15 minutes left to answer questions on some scenarios. I had 6 scenarios in all and 4-6 questions per scenario. The questions themselves were generally much easier (less technical depth) than the 284 ones but I had a real problem with the "what admin groups/routing groups would you create" type questions (and you get 1 per scenario). Admin/routing groups is an easy concept to understand but when you're given a scenario with a head office, regional, branch and subsidary offices and weird design goals your brain just gives up trying to work it out
