There are a ton of different types of ultralights and many are quite good compared to what people were flying in the early days of ultralights (flying lawn chairs). Most "modern" ultralights have wings that are similar in design and construction to traditional aircraft (as opposed to something more like a hang glider). A lot of people confuse true ultralights with other light "experimental" homebuilts. Many of the current popular ultralights can be built to meet the ultralight requirements (weight, speed, fuel) or they can be loaded with options that place them in the "experimental" category (which requires a license).
The FAA recently created a new category that kind of bridges the gap between certified aircraft and ultralights. It is called Sport Pilot which allows people to obtain a simpler pilots license to fly simple small two seat aircraft such as many of the experimentals along with a few certified aircraft such as Piper Cubs. This new license is much easier to obtain and does not require an FAA medical exam. The maintanance requirements of the aircraft are also less restrictive. I do not know how this will all wash out over time, but I still like the ultralight category.
As far as brands and types of ultralights, I guess it all depends on whether your friend wants to build from plans, bolt together a kit, or buy a flying plane. There are many options. I built my minimax (mainly wood) from plans. There are many kits available (such as Kolbs, Challengers, CGS Hawks etc) that vary in the degree of assembly required. Some are mainly aluminum, some are a combination of materials. My recommendation would be to stick with a design that has been around awhile and is built like a small light airplane as opposed to one that looks more like a hanglider!
Ultralights are fun toys. They are not suited to traveling, but for cheap buzzing around on a warm summer evening, they are a blast. I have plenty of time in both "Cessna/Piper" type certified aircraft and various ultralight/experimentals and for sheer "fun factor" the lighter stuff wins hands down.
My Minimax
A customer's "experimental" Spacewalker II that would qualify under the new sport pilot rules.
