I have an SSD in my main pc and while it was a great upgrade, some of the benefits are a bit overblown -
- no one should have to turn their pc on/off. Even with hdd, resume from sleep takes no time. With an ssd boot time is much faster but it really doesn't matter
- yes, apps do launch faster. But I open my apps like browser once and then almost never close them. Again for a lot of cases, if you have an OS install with no bloatware, its not a night/day difference
- games are an exception, since they do a lot of reads. Same would apply to other disk intensive apps.
If you have to pick between extra space or an ssd, its a pretty easy choice. Laptops are a perfect example, since most can only have either hdd or ssd, and I would never choose an ssd, since I can't afford the larger ones.