Old ship design, old (therefore very reliable) technology. Very powerful warp engines. Very heavy ship, not as maneuverable as smaller ships. Multimission vessel. Although the design is almost a century old, there are still a lot of Excelsior class ships in service. Large cargo capacity.
The ship was originally designed as a testbed for the unsuccessful transwarp drive experiment. Under certain conditions, this might make the ship slightly tricky to handle for a less-experienced crew, although this would mostly be compensated for by flight control software. (Of course, in case of computer failure, things could indeed get tricky.)
