Well with Shockwave it's hard to take that cliffhanger seriously... "oh no, the timeline is screwed up!" yeah... I'm biting my nails over that one from Enterprise.
As for the TCW... well it serves no purpose... we don't know who's fighting who and why... there's no coherent plot... and no resolution... so yeah. I think it's terrible. This without mentioning that time travel in Trek is so cliche it's apparently easier to travel in time and screw up the timeline than it is to warp from point a to point b.