I reviewed it several times for German magazines. First of all, just to avoid misunderstandings: "Hollywood" is a programming language, "Hollywood Designer" is a SCALA clone using Hollywood to play its presentations. You're talking about Hollywood, i.e. the programming language, so that's what I'll be reffering to.
Hollywood's main advantage for programming newbies is that there's an internal function for everything you may want to do - no need to fight with the AmigaOS API (in fact, calling OS functions is not even possible). There are native versions for all current Amiga systems and clones and you can compile your programs for all of these platforms. RTG and RTA are properly supported, and the language's syntax is easy to get into.
Major drawbacks:
1. No way to call OS functions means that you can't build a GUI using the GUI toolkit used by the OS (Reaction, MUI, Gadtools...). You'll have to build you own GUI (there are internal functions for file, dir, string etc. requesters though).
2. It's nowhere near as fast as other programming languages (say Blitz or AMOS). You should have a 68040 or better (I'd recommend 68060 or PPC).
Who should buy it:
If you're completely new to programming, or never managed to switch from BASIC/ARexx/whatever to a more powerful language because all the struct, pointer and API stuff is too complex for your taste, Hollywood is for you. Keep in mind that it's targetted at games, presentations, gag programs and the like - it's not really suited for writing a database program.