We timed our road trip to make sure the trail would be open to the peak. It has been undergoing maintenance for a couple years and will last for possibly a couple more (thru 2014) so the last 0.9 mile was closed most of the summer hiking season.
There's nothing particularly interesting about the trail itself other than the various views you are afforded as you ascend Lassen Peak. It's clear the trail will be nicer once their project is done, but there's nothing difficult about it now aside from the elevation gain. That was a bit much for my son (14 at the time) who isn't in the best shape and this was our first day at elevation, but he stuck to it (I'd already bought him the shirt so he had to - LOL) and 3.5 hours later we were finally at the summit calling mom back home. Views were great when we were there. You could see Mt Shasta in the distance. There was a family skiing down some of the snowfields.
Make sure you're prepared for wind and rain even if it's nice when you start.
If you own or manage Mount Lassen, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.