As an owner of one of the newer models (182) it is quite clear many "gripes" have already been addressed.
The doors are more car like - but a very nice 'lock down" (good for anyone who has experienced the automatic door opening on takeoff)
The seats are extremely comfortable for longer flights, the rear seats even recline!
The ventilation is mucho improved - nice twisty standard round airline vents.
Better seat belts (car like three point) , air bag etc. etc.
Now takes 87 Gallons at 15 gph@135kts - 2500 ft. Can go 145 but burns 19 gph at low altitudes.
Things I would like to see are:-
1. Slightly better useable load ( Im on the bigger size..) and tend to take lots of luggage (or the family do).
2. Better cruising speed (160 would be nice
)
3. Fixed undercarriage - there enough reasons for maintenance and failure as it is. ( And it seems the insurers seem to think retractables are a liability)
4. Lower instrument panel- better forward visibility
5. Nicer finish to the instrument panel (loose the "industrial look").
6. JetA1 Fuel since Avgas is likely to skyrocket as it become even more of a burden for the fuel companies.
7. Maintain the short field performance. The modern composites seem to loose out on this.
8. Extra seats! Somehow I always seem to need the a fifth seat, but 6 seaters (with a usable load only suitable for under nourished small people) dont seem popular in the uk.
9. Keep the glass - once bitten you wont go back.
10. Better attention to European requirements. ADF/DME - std. TAS not TIS etc.
The new trainer is bound to do acrobatics (albeit tame) - if they ever make it. Given the number of schools that use the antiquated 152 they would be mugs not to.