I switched to using my iBook as my primary "personal" machine at home around fall of last year, and I like it.
As far as "internet on the mac" goes, if you mean browsing the web-- it's not really a problem, especially if you stick to Mozilla/Camino, Opera, or if you can't let go-- IE for Mac.
As far as installing apache/php/mysql/etc... on my mac, I've yet to go that far (I've got FreeBSD and Linux boxen on my home network for anything like that).
In terms of developing on the mac....
If you're a cheapskate like me, your choice of text editors are slim. (before anyone starts flaming, I know full well that emacs, etc... is nice and powerful, but I prefer GUI editors) Coming from using UltraEdit daily on Wintel machines, it's kind of annoying to find so few good choices (imho). I've found Jedit to be really full featured and nice to use, but its rather "slow." Pepper was a good free editor at one point, but it costs $ now. I'm sure BBedit is okay, but i'm not shelling out $100+ for a stinking text editor. Another option is to use some X apps under the Jaguar X implementation, but again, i'm too cheap (to pay $100 for an OS upgrade). I'll probably cave and buy the upcoming OSX release, but until then, I'll be patient with JEdit.
P.S. If anyone knows of any cheap->free ($50 or less) text editors for OS X (native) that can do extensible syntax highlighting and vertical/block editing among other things, and isnt as slow as JEdit, PLEASE let me know!