Depends what you are into. It doesn’t have the range of restaurants or nightlife as in Taipei. It does have some good restaurants here and there though and there is lots more space than Taipei and easy to drive around, sunny almost all the time. It also has quite a few teahouses and coffeeshops dotted about the centre. There is a two line MRT starting construction, won’t be ready for years yet. There has been a luxury house boom in the city hall area, it has gone more upmarket looking. Overall not bad but yes can be a bit dead. It used to be famous as the hippy hangout of Taiwan and while you can still some dotted here and there that era has mostly passed as has the giant seedy KTV and gangster era, contrary to what appears on the news here Taichung is safe and quiet in general.
There is a new City Hall opening soon, an opera house, conference centre, office park…big changes coming but it is going to be a few years in the making.