I had a 1300 S VTX for two years and 27k miles before I bought my Superglide. The VTX was well constructed, smooth running, consistent and reliable, and it generated a fair number of complements. There are three models, the C is the sportier one, the R and the S are identical except for the cast vs. spoke wheels.
Honda did not spend any more money on the design or construction than they had to, so consider the VTX to be an entry level cruiser. There is a lot of chromed and painted plastic where a Harley would have metal and some shortcuts made in construction, such as cast triple trees and fork braces instead of solid, flange on the tank instead of rolled, fragile electrical plugs, and so forth.
The one issue that I didn't like is the need for a valve adjustment every 8k miles. Have you ever looked for a 4 mm wrench?
I also kept looking for a 6th gear as the engine seems wound pretty tight in 5th. Torque is good all the way up.
The primary factory issues are with the speedo and odo, which are off by 6-10% on every bike, and weak fork bearings. Honda does not consider either to be a factory defect and they do not respond to customer complaints. The speedo error, if it bothers him, is fixed with something called a "speedo healer" at a cost of around $100. The fork bearings are replaced with the roller bearings from either an 1800VTX or from "All Balls", a bearing company.
Operational problems revolve around added pipes and jetting issues, and attempts to improve the air intake. There is a vacuum hose that gets kinked easily that allows pressure to build up in the crankcase. The bike responds by blowing out a seal around the shifter; repair by pushing the seal back in, replacing the oil, and unkinking the hose.
Have him check
Honda VTX Forum | VTX 1300 & 1800 . This is pretty friendly group with members always ready to help. The ongoing discussions revolve around the same issues as on a Harley site: which pipes to use, what oil is best, and the latest in customization. There are links there to a larger site and a tech section.
All in all, the VTX is a great bike for its purpose and one he should be happy with. Its probably not one he will ride for years and years but a good one within its limitations.
PM if you wish.