I email on the Optimus V just about every day, have reviewed Word/Powerpoint/PDF files on it, as well as edited a few Excel spreadsheets... I use it most frequently for reading the news (with the excellent RSS app Pure News in conjunction with Opera browser), and am generally quite satisfied with the VMUSA/Sprint network.
I avoid emailing on it if time allows, but sometimes it's unavoidable. I use the SwipeIt keyboard app and it makes typing significantly faster -- the recognition dictionary/engine is quite good -- than entering one letter at a time. Unfortunately, with the screen size/resolution, the keyboard consumes a good 1/2 of the screen, which forces me to scroll around frequently.
Having played around with the Triumph, I would have gladly 'upgraded', but the issues with connectivity, responsiveness, and other small things (blue tint, battery life, GPS) just far outweighed the benefits of a larger screen and faster hardware.
At the end of the day, it depends on your usage, but for me, a non-gamer, no cell phone (yet on the market) can replace a computer.