I loved just about everything in Plant Tycoon. Sad to say I spent three solid days doing nothing but plant breeding over Easter!! It was my first type of tycoon game and:

Positives for me:

1) Easy to learn - basic soil, water, seed, sell and catch a few bugs for good luck.
2) Graphics - I actually thought these were fine
3) I enjoyed plotting combinations in a spread sheet and the way you can evolve to make up your own ways to play apart from finding the magic plants.
4) Having a limited seed tray for me was a plus because you had to make a decision which ones to throw away or not - hence increasing the challenge.

Upgrades:

1) Pruning sheers to close to _bug_ net - instead of whopping a _bug_ you snipped a flower clean off as mentioned.
2) Vegetable patch idea someone mentioned - sounds good.
3) Closer linking of seed colour and shape to plants.
4) A tally of how many of the same type you have bred for interest.
5) More interactivity of garden ornaments to influence selling perhaps so you could do something whilst they are selling rather than sit back and watch.
6) Move the 'take a photo' button - I keep hitting it when whopping a butterfly!
7) More ways to cultivate and influence price -e.g. whilst bloomed - fungicide treatments, patterns on flowers enhancement liquid, books that could be bought to increase knowledge on maximising blooms, seed production, height of plant, number of blooms.
A greenhouse, vegetable patch/area and herb area (as mentioned) to cultivate in.
9) Sprinkler system - so you can buy and turn it on to water soil all in one go - watering soil is boring.
10) Choice of container - e.g. plant pot for adults/sales, seedling trays.
11) Control of air in the greenhouse -e.g. too hot and some plants die, too cold and some die or grow slowly - so you have to work out conditions for growth in any one batch.
12) Placement of plants - some like sun, others do not mixed into the day/night (which we already see as the sun moves through the greenhouse).