Before reading this post, be sure to read the post on bowed vibraphone, as all of those concepts apply here as well.
While vibraphones will vary from model to model in various ways, they don’t have the extreme differences found in glockenspiels. By this, I mainly mean construction. Some glockenspiels have removable bars, others don’t, others are very thin, etc.
Another issue that many composers seem to be upset by is that bowed glockenspiel is really quite bad at projecting. The only real solution to this is careful consideration while orchestrating.