If you are relying on the rent to pay your mortgage, do you have a plan as to how you will cover any void periods? It is very usual to have a gap between old tenants leaving and new tenants arriving. Tenants do not have to allow viewings (regardless of what it says in your contract, they have a right to quiet enjoyment), or may chose only to allow them at limited times. As well as this, you may need time to do maintenance between tenants.
Equally, you may get unlucky and end up having a problem tenant who does not pay or damages the property. Evicting tenants who do not want to leave can be a drawn out and expensive process, so you will need to be prepared for this.
Agencies can be very incompetent. No qualifications are required to set up as a letting agent in the UK and this can cause problems for both the tenant and the landlord. In one case, when I was renting a property, the agent failed to do an inventory. This meant that I got my whole deposit returned to me despite the agent/landlord trying to claim a portion of it back.
It can be stressful, if you have a tenant constantly contacting you about minor issues, or a tenant who doesn't treat the property properly or who is antisocial, leading to complaints from neighbors etc.
I guess as a pro, it is probably quicker to get someone in as a tenant than it is as a buyer. You will need to have the house in a good state of repair and nicely decorated to get a decent tenant in most cases.
If you find a good letting agent, this may remove most of the day to day hassle (although do be aware that tenants have a right to your contact details and may decide to go over the letting agent's head at any time). You will still need to take time to understand the law etc, and over time you may chose to take over more of the management of the property for yourself.
If you're able to use the rent to pay off your mortgage while renting elsewhere then you'll eventually own a significant asset outright- but you probably won't make a profit until this happens.
You could rent for a year or two and then maybe sell the property if the market speeds up a bit. However, it can be difficult to sell a property with tenants in situ (except to another landlord).