I did this ciruit (opposite direction) in late July a couple of years ago, with ascents of Recondite and Willingdon along the way to spice things up a bit.
It's an incredibly scenic trip - especially in late July, when all of the mountain flowers are out and blooming. Unfortunately, at least when I did it, the mosquitos were pretty horrendous as well, particularly near the Fish Lakes. As mentioned already, the trail can be muddy, deeply-rutted by horses, swampy and, in a few cases, intermittent. It's definitely worth doing though.
The ford of Dolomite Creek, North of Isabella Lake, is by far the crux of the trip. When I did it, I crossed it late in the day and it was near waist-deep. That wouldn't be an issue at some crossings but here the current is fast and the rocks are fairly large, round and extremely slippery. I bivied nearby as I planned on tackling Recondite the following day and, while I was sitting around, another party attempted to cross and were turned back. Probably you could bushwhack upstream a ways and find an easier crossing point if necessary... but just a warning... if there's heavy snowmelt or rain, getting across could be dicey.