Was good at first, but then the writing team took a major dive in season 3, then 4.

"I thought of a plot idea, we'll just make up everything to make a story out of it"
Some really bad examples from season 3 & 4:

-[spoiler] computer is stolen but that's OK, the mouse and KB store previous use [/spoiler]
-[spoiler] making up stuff about poisons, toxicity and more[/spoiler]

and the worst one in Four parts -to start S4 with a major shark jump!
1-[spoiler] whole crazy one about 'making' a unique plastic "missile" so it can't be defeated by radar
2- then using it where there are no anti-missile defence
3- not launching it as a missile, but just using an RPG instead
4- except the core component of the 'plastic' is totally made up "coactive resinase"
5-oops a bonus one. That this melts glass [/spoiler]

Ugh was so annoyed stopped to write this now, may never finish watching S4, so bad only a few episodes in