The only thing Tolkien was passably good at was world-building. Most of his characters are dull, hugely stereotypical, and painfully unrealistic. There's also the simplistic plot, centered on some unsuspecting heroes on a magic quest to save the world from evil and destruction. Much of LOTR reads like a travel logue, as characters aimlessly transverse the coutryside whilst whining inconsolably about their fortunes, and recounting irrelevant history and background information. Tolkein posesses very little in the way of humor, which reads as lame and awkward at best.
You're a little unfair to Tolkien in the sense that you seem to expect his work to work like a Modern novel rather than, as it was intended, as a romantic epic for the modern world. Epic literature has never been about convoluted plots or realistic characterization - it's focus has always been on the presentation of ideals and the heroic power of language itself.
If Tolkien has a weakness, it is the intrusion of his Christian ideals into a genre that really demands a
pagan sensibility. The central purpose of the epic has always been to illustrate the ideal of heroic living, an ideal which, at its core, means being reconciled to death, facing extinction without terror, and bringing meaning to life through the fulfillment of duty in the face of death. In all cultures, the epic tradition exists to teach us how to
be human in the most comprehensive and transcendent sense of the word - epics illustrate, through fantasy, the deeper spiritual and psychological reality of our mortality and humanity. But in constantly denying death, Tolkien provides, not illumination through fantasy, but escapism through the embrace of unreality. In denying death, he denies humanity, and forfeits our natural sense of connectedness to his world and its people.
Still, it's a stirring work, and one that is is powerful in its language and its clear vision of the real meaning of strength, and ought not be dismissed for not conforming to the expectations of modernist realism.