I generally don't like journals that don't have the custom comment page turned off. Fancy layouts are awesome, but if you're accessing the comment page, that means you actually want to read the entry, not be awed by the layout. Custom layouts are prone to having tiny or really light fonts and quite narrow entry boxes - that's just not eye-friendly if you're really interested in what the journal is saying. And it's not like the default comment page is hideously ugly - it's functional and bug-free.

This is, of course, my opinion. I have heard a lot of varying opinions on journal layout dos and don'ts; I think every user sets up their own rules if they've been around for a while.