None of the data the glasses display, except for power, are of any real value to the degree that you need to see them constantly. Heartrate is pretty worthless, and I actually often make a point of NOT looking at distance, like on a longer ride - it can make the ride feel like it's dragging out. Especially with an out-in-front computer mount which are very common these days, glancing down at your bike computer really isn't much of a hassle at all.
Consider spending money on things that will make you more likely to ride, such as clothing for different weather conditions - or if by cycling you mean "for transportation", things that will increase the utility of your bike.
If you want really good mapping and routing, check out the Hammerhead Karoo head units, which run Android. Top-notch routing. The garmins are...OK. Garmin's definitely been far too cozy (little serious competition.)