If you have a memory that goes back aways, you'll probably remember Delicious which is a bookmarking service. Indeed, it used to be the very best service out there, until it got sold and 'improved', at which point everyone went 'yuck' and left for services such as Diigo instead. It's now been improved from the ground up, which I take to mean 'we really screwed up big time, and thankfully we've recovered all the old code and we're putting things back they way that they were and please don't hate on us anymore.'
I took a look (having retained my account) and to be honest - yes, it's fine. It does what it should do. You can use the bookmarklet for adding stuff and you can now link your Twitter account so that you can see what other people are adding, and it has the option of bringing in your tweeted links - which I can't imagine is going to please Packrati.us very much, since while it's not going to kill them stone dead, it's going to be a pretty heavy blow to their service.
You can search for stuff, either on Delicious generally, or in your own feed, which is obviously a helpful feature. You can tag, multi tag - all the obvious stuff. And I think that's the problem with the new built up from the ground Delicious - it's not offering anything new. There's no 'wow' factor, but lets face it - that's difficult to get with a bookmarking service anyway. If you're still using Delicious I think you'll be really pleased with the changes - but if you've moved on to other services, there's nothing here that will bring you flooding back in happy droves. It's a case of 'too little, too late'.