These are honestly the two biggest criticisms I hear about Vim; and, if they're features you really do use often, I don't really have any good response in store.
Regarding refactoring; I don't really miss it at all. For renaming, I simply use vim-ack and find where a rename would need to take place. In most cases (for the projects I work on) we're talking about the difference of maybe 30-45 seconds.
Intellisense is cool; there's no doubt about it and there's not really anything that comes close in Vim (omnicompletion really does pale in comparison). That said, the only type of projects that I've ever felt I really used Intellisense were sprawling Java applications. I've never missed it while working on JavaScript or Ruby projects (and, anecdotally, I've heard many C and Python developers also talk about not needing this feature).
Ultimately, Vim benefits me with overall productivity (for example, it takes Vim an order of magnitude less time to start up than Eclipse on my Macbook Pro--and then proceeds to lock up every few minutes while it does GC or whatever the hell else it does to just randomly stop from time-to-time). While I'm in the mode of writing and editing code, it's also significantly faster and easier on my hands and arms to be totally keyboard focused.
All that said, it's a really text-centric form of programming that is somewhat different from the hand-holding (not meant as derogatory; just a statement of fact) and all-in-one approach that an IDE can give you. There are some contexts (Java) that just aren't well suited to editing in Vim (but they're probably not suited for Sublime or TextMate either, honestly).