So far I don't like it all and strongly prefer the alias approach.
Aliases are much faster to edit - I can see and sort a hundred different email addresses across single or multiple domains in an account, all in one 'gulp' on the manage addresses page vs parsing filters. Worse, now I have to do SOME in one place and everyone else in another. Plus, it makes succession of my role as admin harder since the aliases are now tied up in my personal email.
Another problem I'm having may be solvable if I were smarter with filters. I have a friend with a domain she uses simply to - you guessed it - forward her 'branded' email address to her personal AOL account. I set up a filter that labels the mail as a forward to her account, forwards it, and archives it. I want to delete the mail after forwarding but felt I needed to run the filter a while to make sure she wasn't going to lose anything - so now mail is passing through my account I'd really rather not get (lab results and so on - none of my business). Also, our interests overlap on several committees and so on and I'm not Gmail-smart enough to figure out how to set a single filter that tests that the mail INCLUDES her address but DOES NOT have ANY of the twenty or so active email addresses that I use for various roles (forum admin, web admin, publications committee member, paypal admin, blah blah - these aliases I use so I can use smart labeling and workflow on my own incoming mail). So the trick is to filter-forward-and-delete ALL and ONLY mail that ONLY should go to her, but filter-forward-and-file-appropriately mail that I should ALSO be receiving. Argh.
I also use it - carefully, to avoid loops - to cascade aliases so that for instance a 'change my contact information' formmail will send to 'firstname.lastname@example.org' which then itself aliases to 'email@example.com' AND 'firstname.lastname@example.org' AND 'email@example.com' and 'firstname.lastname@example.org' so we can each update our independent databases.
So really, I still consider email aliases a fundamental and basic domain tool.
Gmail rocks and I love it to death for handling the metric ton of mail I get from various sources, but it's not as good as the manage email addresses control panel for managing EVERYTHING and therefore having to do it two places, depending on the poor member's personal ISP, is a hassle.